Anyone that says you don't need a cleric in D&D is a fool or plays with DM's that never challenge them. That said, there's ways around not having one, but it should hurt. I'm in favor of it hurting in Baldur's Gate 3, but I know that won't be the case. So far in EA? Absolutely not the case. You don't need a cleric whatsoever. I certainly bring one, but in Baldur's Gate 3 even moreso than pen and paper I find healing spells almost useless. Food heals you and is ultra abundant in between fights. Healing mid fight is usually not really worthwhile in 5e unless you're just getting someone up from 0. It's one of the weak spots in 5e.
Since Larian is adding some of their own flavor, I would really like to see the game made more consequential. Maybe reducing the number of times you can be downed in a single fight to once before dying, or something. The 5e yoyo mechanic is strong here with help actions.
In my 5e games I have a custom rule where anyone who goes down to 0 just takes a point of exhaustion each time. Exhaustion hurts big time after you get 3 levels of it. Even 2 hurts badly.
