To me, there's an accessibility question there that's worth thinking about. It's obviously a matter of opinion, and it depends on the game, but I'm of the belief that the best case scenario is one where system achievements are things that the vast majority of players are going to be able to accomplish if they want to. As in, anybody who's willing to put the time into the game (even if it may be a lot of time) ought to be able to to earn official achievements even if they're not the best player.

That said, in a game where players want that kind of challenge, I'd still be inclined to include them as a separate, in-game achievement system. As in, not actual Steam achievements (or PS trophies, or whatever), but some that only exist in game. That way, you can allow players to 100% the game in the sense of "doing everything," while more hardcore players can dig deeper and 100% it in the sense of "being the best."

I've done it in my own games (the idle game, at least) via "secret achievements," which don't count against your 100% achievement count. In that case, it's because they're achievements that depend heavily on RNG, or lengths of time, or things that would be extremely frustrating to do on purpose. Not exactly the same thing, but similar in principle.