One thing overlooked is how flexible dual wielding can be. DW fights aren’t typically the in your face kind of fights. You duck and weave your way around the battlefield.
I got Asterian(sp) set up as a thief and dual wielding scimitars and the versatility was pretty powerful. He had those boots that give mobility and that helm. He pretty much owned the battlefield.
1: Backstab one and kills, cunning dash, bonus hit on another.
2: Use two bonus on one then longbow on another.
3: Bonus attack, cunning disengage, run as far away as possible, longbow,
etc
These don’t include the 3rd bonus action granted by helm. He pretty much danced the battlefield.
This makes sense. On melee rogues, I fee like it's the Standard Option™ to Dual Wield, either because of the extra chance in tabletop to get sneak attack, or the extra bonus action usages in BG3. A dual-wielding rogue is just better than a rapier-wielding rogue. If you do need to use your BA for something else, you've lost a paltry 1 damage by using a shortsword instead of a rapier.
The main problem imo is that, as @OP says, Fighters, Barbarians, and Rangers can't usually make good use of dual wielding. It's just so suboptimal compared to wielding a single weapon, and that's even without taking into account GWM. You either get a shield for +2 AC, or get so much extra damage using 2H weapons when Extra Attack comes online. And in BG3 it's even worse due to the plethora of homebrewed Bonus Actions that single-wielders don't have to sacrifice damage to use.
