There's absolutely nothing wrong with social dancers.
However, they usually represent a substantially different approach to dancing. Of course it's a spectrum of possibilities, some very carefree, others fairly focused on gaining mastery. But it is ultimately a different community of people.
Two examples of where you start to get some real cross-over are former competitors who did it for a while but decided it was not their end goal in dancing, and increasingly some of the non-competing students of younger teachers (who themselves compete in the amateur division). The later group are interesting, because they inherit some of their teachers' attitudes rather than the usual studio/social ones.