Earlier quoted context omitted.
except for when things go wrong and they just say "I'm using firefox and your site is broken".
and then you say "well, is your firefox updated?" no more of this "i'm going to stick with version 3.6 for now because i prefer that" nonsense. there is only up-to-date and outdated. yeah, it's a subtle and mostly psychological difference, but it is a difference.
There has to be a line drawn - where do you draw it? If 5.0.1 came out yesterday, do you not support someone who is running 4.8 which came out 3 weeks ago?