It has nothing to do with this being a switch game and everything to do with linear progression and not constant and cheap reuse of existing assets we have already played though. Mario 64 had 120 stars, most of which all of them could be achieved by getting while they were in the map for the first time (If not all of them) leading to a very well paced platformer. That isn't frustration. That is fun. 90% of SM64, when you were done, was fresh content done once.
Now here comes SMO. 50% of this game is going to the same places you already were before and seeing which nook or cranny you missed so you can see the new levels to get to the "optional" meat of the game people care about. That isn't fun. That's frustration. You say it rewards that game play and those levels are optional, in a game where playing through levels and their unique design is why people buy it. I wouldn't call that optional.
There isn't anyone I have ever spoken to in my lifetime of gaming of when bringing up the new Mario game of whatever console it was on saying, "I cannot wait to collect those stars and moons!"... It was always, "I cannot wait to see the new creative platforming levels... they always come up with something good and it's a blast to play!"
Collections are a way to get to the meat of the game they care about. Not the other way around.
I won't knock you if that's why you play it... All the power to you. Saying it's objectively wrong is silly.