It’s true: there is a great deal of fragmentation. This is very similar to the situation for Lisp and Linux. The solution is to coalesce around a de facto standard, which in the case of Smalltalk is open source Pharo. Pharo is easily the most actively developed Smalltalk today. As the article points out, Pharo has produced many innovations in its brief nine-year history, and it continues to move forward at a very impressive pace.
I don’t use commercial Smalltalk but I understand that Cincom Smalltalk, for example, is extremely well-supported including good documentation. Enterprises that need this kind of support can certainly afford to pay for it.
Cincom also provides a free Personal Use License for Smalltalk, which is nice.