Totally agree, make your way out of something without combat should award at least the same XP than combat.
In DOS2 this is a very important flaw of the game, if you talk your way out of all the situations you can , you end being underleveled. Hope Larian dont make the same mistake again.
As a side note, when i'm DM of any game i always reward more XP for solve things peacifully either by rolls or by good interpretation. And as far as i know many people do just that. So i call it a very common mechanic or unwritten rule of a RPG
