What people call "hard" is basically being the victims of the poor RNG this game is so fond of.
Fights go radically different based on whether you're missing half your attacks or not, which is why uniformly this game is all about every single class playing like a rogue and sneaking around to high ground.
It's very one dimensional combat with an incredible amount of cheese available in terms of consumables and environmental actions like pushing something off a cliff or detonating a barrel doing half the HP of a boss but a spell that uses a spell slot if it's lucky enough to land does around 1/10th their HP at best.
Pretty much. I don'y agree on the missing your attacks part, i've played games where missing is basically all you're doing at higher difficulties (Kingmaker), but the rest is pretty much how it is. And i would also add that, for now, every hard encounter is basically the same. At first 'weak' minions standing on highground and spamming ranged aoe spells that deal high dmg/status effects, and then the boss doing the same but with way more hp and in melee range.
If it was the same in DoS i get why people say it gets tiring after a while. It's not there for me yet, but it's pretty stark there are no real tactics, just one way to handle things and having to do it over and over again.