I think it's been said a lot over the past 8 months or so, but they just have a bad power curve for the campaign. A lot of it is fixed by having access to second-run stuff like infinite supports and tier 5 supports and twink weapons, but it's just rough.
Act 1 is the most punishing because you just don't have tools
Act 2 gets better because of new skills/support ascendancy
Act 3 layouts suck, but most builds feel "good"
Act 4 is all over the place but USUALLY by then you're either crushing it or you fucked up bad
I think it should be a breeze to walk through almost all of act 1, maybe Geonor a bit of a skill check (low damage, just mechanics), then act 2 let you fuck through, act 3 after your 2nd ascendancy start difficulty, act 4 gut check you like act 1 currently does. Respecs should also absolutely be free or near free before level 65.
I've taken literal broken classes through campaign season starts at least twice now and it is brutal, but once you know what you're doing it really isn't THAT much different than PoE1 campaign. If you're a "6 hours to maps!!!!" in PoE1er, you should be able to get to maps in PoE2 in 10-12 pretty easily.
That said now entering the map engame the REAL questing begins! There's so much fucking stuff I think it's a bit much. That and 1/3 of the shit being soft-lockable is a big problem. I'm scared to advance shit like Hilda because she can literally nuke expedition. I just did every breach node and I can't even allocate one of the last two passives (probably because haven't done a breachlord, but it doesn't SAY that). Shit took PoE1's mass of complication and just ported it right over. It's good for eaters, but it's going to BREAK casual gamers which PoE2 was set up to be the game for.
They done added too many ingredients and too many cook times.