You assume there's anyone actually doing that. As
@Chaosmancer said, many players simply think 1st level is just the place you
always start. And many DMs have no interest in changing their minds about 1st level being the place you start, so it creates a self-perpetuating cycle.
People do lots of things not because it makes them happy, but because it's just "what one does." That doesn't mean they
hate it either! It just means that you cannot say, "Ah, yes, people do X, therefore people like X."
That kind of thinking leads to all sorts of really, really wrong conclusions.
Women must not want pockets, since they keep buying clothes that don't have pockets! I guess women
like not having pockets! (Spoiler alert: Every woman I've ever spoken to about this issue
hates the fact that real, functional pockets are so hard to find in women's clothing. Yet for some reason, this hasn't changed, across my entire life. Why? Aren't there companies out there who could make
so much money if they would just make women's clothes with actual pockets? And yet....)