So I can't speak for everything regarding Old School vs Vintage, but I've found the breakneck pace with which people demand change in Vintage to be extremely harmful to paper Vintage. Since MODO moves so much faster, people are tired of a new metagame in a week and begin to loudly proclaim on social media and wherever else that the format "sucks" and that we need a change and X should be restricted and whatever else.
On the flip side, we used to have one Vintage event every few months. When you have zero investment in a format that you're sure is going to change by the time the next event comes around, it's really not something you want to get into. Add onto the fact that people loudly proclaim the format isn't fun when you've barely begun to even play it, and it's not hard to see that there is not much desire to play. We no longer have Vintage events every few months.
Old School, on the other hand, fulfils this desire extremely well. This is why I don't believe proxies will do much to change anything since the cards clearly exist. The desire to play Vintage as it currently is just isn't compatible with what players on MTGO want.