Sure, the mechanics of speeding the progress system. Of course, it has SOMETHING, or else it'd just be pressing a button and that's it.
But, if you think about it, you can't lose. You can't win. You just see numbers going up, and to raise them you don't need any skill whatsoever unless you are directly competing for a limited time with another from scratch. But if you go to that route, you can compete over anything, doesn't make it a true video game or having game mechanics.
> ideally with challenge you want to make the player use everything at their disposal to overcome the difficulty, instead of limiting their options
That's the issue, when the devs throw stuff at you that breaks the game, particularly if you have to farm for it, just makes it so it encourages people to beat the game by farming and then reduce the actual challenge the game has to offer. You make them waste their time and then make them not appreciate your game as much, since they are steamrolling through it.
Instead, all your options should be decently balanced, or at least don't promote the "farm = win" crap. Again, that has lead to games just becoming progress systems now. Mega Man Zero is a transitional title between arcade action and progress system fest, it's still quite on the former side but it sacrifices some core values an design to pander to progressfags (and storyfags, who would rather farm to read the story than to actually engage with the game proper).
And yes, SotN is one of the worst examples of an action game ruined by being too heavy on progress systems. This is my point, but some people get triggered when I mention this stuff and think I mean every game has to be an arcade or something. I still have fun with the MMZ games; however, for SotN I'd have to do some sort of self-imposed challenge, it's too far into the progressfag spectrum (and intentionally, the devs wanted the game to have a "wider appeal")