Only Zelda Classic quest makers don't make the quests too hard for general players stray sheep. But in almost every other fan-made game, there are plenty of people making challenging material for others all the time - Geometry Dash, Bloons Tower Defense 6, Mario Maker just to name a few. I think its because Zelda made the modern Zelda game too easy and only the crowd that likes easy games went for it.
I'll admit some players give bad ratings for challenging quests - there's no doubt about that. But who cares? People can rate quests badly until the cows come home but it'll make zero difference in the end. Ratings only matter if the person rating the work is the one paying for it. I'll tell you this - even if everyone in the whole fanbase rated my LoH and LoH:IU zero stars it would make zero difference and they would still be exactly as they are right now.