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!”.
Because ban evasion is an everyday occurrence here. Someone gets banned for being a jackass, and 9 times out of 10, they come right back with a brand new account and come in hot with inflammatory posts and a chip on their shoulder.
Or trolls just troll - spin up new accounts over and over and throw out rage bait or whatever their shtick is just to be a dick.
Combined with the fact that the fediverse’s growth has been a bit stagnant lately, when a bunch of new accounts suddenly pop up, they’re rightly met with suspicion until they’ve established themselves as being here with good intentions.
Not saying new accounts should be ostracized, but given the context of the current state of the fediverse, being suspicious of them is warranted.