As far as I understand it, that is nothing more than an urban legend based on the fact that 5.0 was a terrible, rushed release and not meant for production (it was also marked as such). That mistake has not been repeated since, to my knowledge.
I mean it's obvious that you'd want the latest release, and there's no release numerically higher than that one. But I understand, for some, laconic and prejudicious snarks are more pleasing than trying to understand what the interlocutor is trying to communicate.