I haven't played MM (my loss), but to me it seems something depends on whether this frog-talking quest is central, or at least helpful, or just entirely optional.
If it's vital to finishing the game, then I can understand some frustration around it. If it just gives you a heart piece, then... suck it, "completion" isn't supposed to be easy.
Either way, I think you're quite right. It often seems to me that people who make YouTube videos commenting on popular culture are mostly motivated by "finding something to be angry about", on the basis that the more they lose it and shout at the media, the more views they get.
Only yesterday, I was watching someone else watch a video (how deep does this go? - stay tuned, not done yet) made by some YouTuber watching Scooby-Doo, the (live-action, 2002) movie. This YouTuber argued passionately that the movie wasn't funny, wasn't true to the characters and mythos of Scooby-Doo, and was particularly unfair to Scrappy.
Okay, I can see the "mythos" argument. Instead of some goon in a Halloween costume, the movie for the first time gives the team genuinely supernatural elements. (Although I'm not convinced that's so very different from some of the science-fiction BS that's been shovelled into the TV series for decades.) But for the rest, I think the reviewer is just so full of **** that he can smell it in his own nose. In particular, you can't be unfair to Scrappy-Doo. That encephalitic mutt was pure comedic poison from the moment some desperate rancid chair-warmer in ABC suggested he be added to the roster. The movie's treatment of him was blissfully cathartic.