(Everything he said)
Aside from card pool, card prices, and support rarity, there's also the fact that our tournaments can stretch for a long time. I'm not sure if this is the same for other formats or not, but every Star City I've attended has been quite a long day.
JP, I always thought the logic went more like this:
"It's a format for adults because adults have the dedication, have the maturity, have the patience, and have the cards."
But now the cards don't matter, a lot of our players are immature regardless, decks win sooner (in other words, "fuck patience") and we have proxy tournaments.
I say if kids want to dedicate to playing Vintage, then throw the "adult format" bullshit out the window. We aren't playing with the nekkid lady Poker cards at some high-class strip bar, after all.