What you gotta keep in mind is that this game is effectively "D&D as intended", not "D&D as played by people who only care about number crunching" or "D&D, but really just 5 friends memeing while one dude kills literally everything no questions asked" or whatever else may have happened in groups you played with.

This is a deeply strategic roleplaying game with some difficult conversations and impressively hard combat. The game doesn't put up invisible walls and say "if you tried that you'd die, so instead you can't", it lets you try and fail. Or if by some miracle you win and get some items way above your current power level, you can use them immediately unlike other RPGs that say "you have to be lvl 5 to hold this sword". You wanna jump off a cliff? Game says "Okay... you died. Wanna reload?"

D&D 5e rules are there, but they're operating sort of like the laws of physics. The heart of this game is its phenomenal writing and the sheer openness of the world it sets up for you to explore. You could argue this game is a full-blown immersive sim just because of how it sort of hands you a pile of problems and you build tools and skills along the way to overcome them.

Yeah, it holds overall mass appeal. It's a good roleplaying game that happens to be in an established universe with known mechanics. If you play by yourself you have more than an entire party's worth of companions to learn the stories of, and you don't have to worry about playing with degenerates or weirdos. Unless you consider the NPC a degen or weirdo, but thems the brakes.