Like, I’m probably answering myself here but I think it is pointed out by gatekeepers who can’t stand the idea of community growth and everything should adhere to some other unfound arbitrary way to keep things ‘pure’ in a community.
When they forget that they too, started out as new and that they too probably have had other people sneer at them for simply being new. So now they go around and pretend this is some kind of ultimate shut-down insult to people who’re just trying to contribute to the fediverse by devaluing it by saying “OH U JUST SOME DAY OLD ACCOUNT, NOBODY SHOULD MIND THEM!”.
it’s a heuristic. evaluating every one-day-old account on its own merits is a lot of mental load, so people take shortcuts. if you’re an active poster, people can look back through your comment history to get context on your perspective. it’s hard to do that with someone using a brand-new account. in a month, nobody will be saying that to you any more.