Yeah, that's another big point i missed. ARPGs tend to have a "difficulty cap" where if you are geared/leveled enough you can beat the content - this makes so many more builds have representation and the fantasy of "having your own personal character" is very strong, because it translates directly into the playstyle and game pace.
When you put things like organized group play, tactics/mechanics, or infinitely scaling content this kinda falls down, as you have performance requirements to "meet", be it doing a task in time, or compare your speed to other players. You can see it in D3 - any build can do everything, but climbing GRs. So, everyone went for the same builds because they were the strongest at it and there was nothing else to do.
In D4, when they said that dungeons will have a level cap, i was genuinely happy. This coupled with good balancing makes so many more builds can clear content and farm gear, as if you reach the "doable" threshold, a build is automatically good to go. You can add clear time ladders, but that is just an addition and not the main focus of the game.
In that regard, another thing that ARPGs nail is the total lack of competition. I mean, it's a competition against your self and putting yourself objectives to reach, without having to deal with stuff like "need achievement to join group". I know it's not a game's fault but a player's one, but if game structure doesn't really allow for it, then it dies automaticaly.