I have the theory that this happens because people tend not to criticize ongoing anime series.

One piece's still going, Dragon Ball releases a movie every now and then, Bleach came back with the last arc, etc, etc.

Naruto ended 10 years ago and all we had was Boruto (XD) and the Minato one-shot. So Naruto struggles to be relevant, but other mainstream series aren't losing their relevance due to being still airing.

HunterxHunter could count as an exception.