TerraDave
5ever, or until 2024
There's a bit of a hint here that this idea that leveling up is important comes from new/younger gamers.
I don't agree with that at all.
As I have gotten older, I have less time to spend on gaming, don't want campaigns to go as long and know they won't, and hence want, on a per hour played basis, faster leveling.
IIRC, Gygax's own expectations in the 1e DMG were about 1 year of game = 10 levels. Or something to that effect. So, it's not really something new.
Moving through a sequence of old school mods basically required a good pace of leveling, and we know that they had the treasure for it.
Though, I will concede that with a narrower sweet spot (you want to play in levels 3-9 or so), charecter turnover, henchmen turnover, and the importance of magic items as a reward, slower leveling in an "old school" game is fine.