Suppose the following maxim.
Goal: satisfy basic needs: food, water, sleep, etc.
Method: having a specialization, getting money for work, spend money to satisfy basic needs.
Conditions: capitalism, everyday life.
Now let us suppose we have a particular specialization. A cook, for example. We do not do others' people work. If everyone was a cook, no one could provide food to be cooked, therefore goal would not be acheived. It appears, the only method satisfying this maxim is to be a jack-of-all-trades who can both work on farm and garden, cut meat, gather fruits and vegetables, cook them, etc.
Well, people leaving in a village typically do that. But this lifestyle is incompatible with town/city. I am not even sure Kant himself had a farm, cut meat, etc. (but that's irrelevant, even if Kant did not follow CI, it does not show CI is bad) Also, we have strong reasons to encourage division of labor, so that not everyone actually had a farm, garden, etc.
Does CI actually restrict such division of labor?