Why do players complain when powerful loot is tied to a hard activity?

I have no idea if this a hot take, but the pinnacle of activities (Master Raids, GMs, Trials, etc) should have the best Weapons/cosmetics available in the game. Why are Adept weapons so insignificant compared to their non-adept counterpart? Why don't we have cool ass Armor Ornaments for going Flawless like we did with Trials of the Nine?

I'm genuinely confused, Im not trying to be rude to the players who may not be able to do those things. Destiny is honestly the only game I've experienced that is so afraid of properly rewarding skilled players.

Why isn't this an issue with other MMO's? Or even other Video Games in general?