So does this mean if one disagrees with or rejects Marxism in at least some way, e.g. rejects the notion of a "classless stateless society [a type of anarchy]" as the ultimate and best form of society for humanity, or reject the notion that the economic structure determines everything (economic determinism), or rejects the Marxist theory of social evolution, then the whole edifice of the Continental philosophy collapses?
The full quote from that link essentially already tells you as much. Arguing that attempts to find logically valid or sound arguments in her work have lead to self-contradiction and internal inconsistencies.
So the commenter "Jaime Ravenet" goes on playing devils advocate and pretends "But what if these self-contradictions are just a version of 'dialectics' a philosophical approach of having a constructive debate between opposing viewpoints, where the goal is not to win but get closer to the truth by studying seeming contradictions. Which was then developed in continental philosophy into a discipline where you would do that on your own looking at a thing and it's opposite and which Marx attempted to drag from the mostly theoretical to the empirical world."
So he's essentially joking by saying "what if she wasn't just wrong and couldn't argue properly, but instead was making a sophisticated argument using deliberate contradiction. Genius ;)".
And which he subsequently dispels as an alternative as it would be totally insufficient at proving that point. It's probably something like saying "The English language is the most useless invention in all of human history". To which the response would be "So why did you write that in English?" and most importantly "WHY? That's insufficient to prove that.".
And with regards to your particular question: No, that does not mean that if you contradict with anything that Marx said, that this would lead to the collapse of the entire continental philosophy, which has been noted by others already would be in need of a definition as it predates Marx and has lots of contributions that do not reference Marx or his apply his methodology. Not to mention that the idea of dialectics wasn't something that Marx invented either. At the time it was something popularized by Hegel.
What Marx might claim ownership over is dialectic and historical materialism. So the idea that one could apply dialectics not just to ideas to explain real world object but to real world objects to understand their evolution.
Which you could argue is the concept that led to results such as in:
- (reject) the notion that economics determines all other social structure,
- (reject) the progression tribe -> slave -> feudal -> capitalism -> socialism -> Communism evolutionary theory
Now whether you reject these is just your opinion and as such of little significance. The more important problem seems to be that there are occasional confusions between logical contradictions (true/false) and conflicts of interests (class struggle) in that system and that the ability of a philosophical system to live with contradictions can easily push it into the domain of pseudo-science, cause if your theory can explain a thing and it's opposite at the same time, that is not an indicator of a good theory, it's actually awful as it isn't applicable anywhere other than in hindsight.
Apparently Marx looked at historic and material progressions and saw that:
tribe -> slave -> feudal -> capitalism
As well as the fact that the most recent change(s) (e.g. French Revolution, 1848 Revolutions etc, Paris Commune) had indeed happened by a class struggle and a revolution and then tried to extrapolate that trend. That societal makeup follows the conditions set by the mode of production and that the development happens via class struggles.
Kings try to get more stuff hence abusing slave labor, the ever increasing management of slaves leading to feudalism and an aristocracy, the need for ever more production leading to a reliance of a middle class with advanced means of production leading to capitalism and the necessity for a proletariat to build and run these machines leading to the point where they can do it without the owners. And further on to a society where everyone is working and consumer and were one collectively decides what is produced for ones own benefit ending the class struggle of exploiter and exploited.
The problem is that this is only one explanation from a specific point of view of history on history. It's still a matter of debate (or rather research (hopefully)) as to whether "capitalism", the accumulation of capital in the hands of the few that enabled them to invest the collective work force to their own benefit, created the increase in technology or whether it was the invention of technology that led to an accumulation of capital in the hands of the few.
In the first case you'd just need to gather lots of stuff and inventions will follow naturally, in the second case you'd need to have ideas first.
Just because there is an obvious correlation between accumulation of wealth and capital and the development of new technology, it's not quite obvious what leads to what. Not to mention that the relation could go both ways and that both explanations could be correct in some places and wrong in others.
So yeah that specific result of a dialectic idea of historicism might be wrong, but that's not necessarily a nail in the coffin of using dialectic ideas.
Similar to the economic conditions determining the social structure. Like to a degree that is as well based on real life observations. Both in terms of similarity like the structure of organizations very often models itself after existing models. So military, church, politics and companies, often modeled their hierarchical structures after each other and an economic advantage also often enough creates a social advantage and vice versa. So again there is some correlation though the direction of causation and the strength and reliability of that correlation can still be disputed.
Though again does that invalidate the idea that one could learn something by employing dialectics? Not really.
reject the notion of a "classless stateless society" as the best form of society, or as incompatible with human nature or otherwise unattainable,
Sure Marx might have arrived there via his class struggle dialectics, but lots of other people have arrived there before and afterwards not employing that. Like that is not just a Marxist utopia, isn't that literally how "utopia" was characterized? Like utopia means "non-place" or more abstract "not-(yet)-existing place" but when described it usually looks something like that.
Also what's the alternative? Like anti-classless, so strong social hierarchies and a rigid caste system? anti-stateless, so totalitarian authority of the state? Anti-society, so extreme individualism to the point of being a hermit not relying on anybody else?
There are people who support 1 or more of these aspects, but at least since the enlightenment these have fallen massively out of favor despite having occasional comebacks though usually even in those cases their true intentions are at least somewhat hidden.