I do not think that XP based on rapid completion is suitable to RTwP games (if bg3 is going to be like that), it is more a TB thing or tactical games like Valkyria chronicles or Fire Emblem.
Even in games that use xp based quest outcome, not in enemy killing like VTMB you can have different xp rewards depending on how you complete the quest, skill usage, etc. ej: Not being detected, achieve a diplomatic solution, rescue all hostages alive, etc.
