3.5 was edition I played the most. It was a reason why I quit RPGs for nearly a decade because I hated it so much.
Every time I see another meme about how amazing 3.5 Tarrasque is, I remmember how amogn actual 3.5 players Tarrasque was the biggest joke. It was always brought up as definite proof designers have no idea how to make good monster. It was laughably easy to beat. A wizard could casually solo it, the same abilities people now miss in 3.5 amounted to ribbons. It was a laughingstock, forums had 100+ pages discussions how to fix it and general consensus was it';s beyond saving. It was first proof in 3.5 if you cannot use magic you're only good to roll over and die.
I honestly don't know if everyone claiming 3.5 Tarrasque is such a horrifying monster are trying to rewrite history or unintentionally proving what a broken, unplayable pile of garbage 3.5 was, if it's biggest punching bag is actually dangerous in a different, better designed game.
I play 3.5 for a few years. One of my groups swore by it. It was... textured. When you call it a steaming pile of shit, I see your point and honestly agree with you. But I will say it was... completely what it was. It wasn't well designed, but it was immensely interesting. 5e is all of 3.x, but with the interesting parts sanded down. In my estimation, that makes 5e the lesser game.
3.5e just had some much room to explore. Yeah, some parts sucked or didn't make sense, but I think that really led to some interesting characters and fun moments in games. I haven't played 5e much precisely because it's so smooth in comparison.