Unfortunately I've seen some of those enterprise and long-term-support Linuxes and the "if it works" condition didn't really hold, e.g. gaim crashed if it wanted to play any sound, youtube didn't work, etc.
In one sense the Linux distribution model is great, because one can get all software from one place and they (are supposed to) work well together. On the other hand applications are sometimes too thightly coupled together, if one needs a new version (to fix a bug) of an application, due to dependency issues a whole lot of other applications have to be updated (which is bound to introduce new bugs). I mean I don't think that a new Winamp on Windows will ever make me install a new MSN, but I'm not that sure about a new audacious bringing on a new pidgin. It's hard enough to make one application relatively bugfree, but it's much harder to do it with a whole distribution.