So basically, what your saying is most companies don't want to split even if they can? What's wrong with having two people work one division while the other th

So basically, what your saying is most companies don't want to split even if they can? What's wrong with having two people work one division while the other three work the other? What do you think is preventing that from happening? Yes, some companies really do split the functional divisions of HR, marketing, product management, finance, etc. They are rare but they are quite successful otherwise I wouldn't be asking this question to figure out why more companies don't do the same?