so mouser specifically doesn't want to sell to companies, only individuals not selling the things they design with mouser-purchased products?
No, no. Let me elaborate.
In every country there are well established component distributors (Rutronik, Avnet, Arrow...) who have long term agreements with manufacturers (Maxim , AD, TI...).
There are also small players who will sell to companies whatever part they want, they buy from ebay, amazon, alibaba, mouser, digikey or any small company that doesn't have a distribution network. These small players are useful because they lower the transactions (administrative) costs and the supplier base for their clients. One of these suppliers can source small parts from hundreds of different places to one company, hence the advantage.
Now you see the dilemma when one of these distributors tries to buy from mouser a reel of Avago optocouplers only to sell it later to his client in country X. Well, the official distributor in country X doesn't want that and agrees with the manufacturer to forbid mouser from doing so.
The rabbit hole is much deeper than this anyway