Pitching in to also agree on EA leveling to be too fast.
Broading the XP problem:
You can see the players base as an XP spectrum. On the left the rushers going for a fast play and only going for the main quest. On the right the completionist. Somewhere in the middle are the average Joes larian are targeting.
Problems are two: 1. in dnd the DM should adapt content to its player base. Larian is making a preset one size fits all. This is a limitation from porting to the game format.
2. Anyone to the left of the average Joe will experience an increase difficulty forcing them to either improve their skill or add more side quest (essentially it solves itself). However everyone to the right of the average Joe would outgrow the content and game would fill too easy. A problem that not only doesn't solve itself but reinforce itself (as you would go through content even faster).
That specific group is the problem. Only solutions I forsee for those are a combination of: higher difficulty preset (moving Joe to the right) - easy to implement and must have but not so great because the player doesn't know before it first playthrough how much he is far from the average Joe. Diminishing side content XP rewards (not ideal and boring but effective). Capping max XP given per area (basically cap how far the completionist can drift from the average Joe, has the advantage of not shoving a path: player can play whichever content and decides to stay in an area or move further if he hits the XP limit).
