I think the point is that in the MRV there are night options, but not as many as other areas and you do have to look for them. When I skied SB I was often too damn tired after skiing to go out at night....
I guess it depends what you're looking for. One of the things (other than Sugarbush itself) that originally drew me to the valley was that it wasn't commercialized like Killington for example. There's plenty of options and I never really thought you had to look too much for them in the MRV. I stuck with just mentioning some of the more popular "bar" places. There's plenty of other great restaurants too that are more laid back (Peasant is a great example for an awesome meal at reasonable prices with a well thought out wine selection in a relaxed environment). For me that's all I need after a good day of skiing if I decide to go out somewhere instead of staying in and cooking. I'm not looking for a club to party at all night. I want to get up bright and early in the morning to get back out on the slopes.
And for the record, I was in my early 20s when I first discovered SB. That might put me in a bit of a unique group as many people my age generally do prefer more of an active night life I think.