And no, being able to Long Rest after every fight is not a fix, it's part of the problem.
Correct. It is a snowball effect that Larian did in order to meld 5e and DOS as much as possible, but maintain the illusion you are still operating under 5e mechanics.
As I posted in other threads about this, you can dissect every layer of the BG3 combat to see that Larian homebrew is meant so that their DOS base is not completely alienated in this game. They are not catering to 5e people, they are catering to Larian loyalists that may not have a 5e background at all. It is in their interest not to alienate their base.
Larian not only did not put parameters around the Rest system, but also tied all the major cutscenes and story progression to resting in order to passively pigeon-hole you through resting anyway. The game is literally designed so that you are not in those tense and desperate situations of being caught without many spell slots before you need to pass difficult content. It is anti-5e, anti-DnD.
After watching gameplay footage from others on various sites, I realized the average player that is playing this game in EA is not very good at the combat. Even though the best of us know that the combat is super easy and formulaic to the point of drudgery at times, the average player sucks at combat. This is why there are a lot of complaints about the game being too hard, even though you literally can fight every single fight with all spell slots available on every character if you so wished.
