But WotR has mobs because you are supposed to feel like there are demons everywhere. That's part of the story. You are in a hellscape full of evil demons. Meanwhile, BG3 almost feels like there aren't enough goblins or spiders or creatures in the bog.
Even compared to similar RtWP games, Owlcat have always been excessive in their amount of combat in general. It wouldn't surprise me if there was more than in both Icewind Dale games, even (which have more variety too -- and in IWD 2, even the environment was a thing, such as barrels exploding or orcs using war drums to call reinforcements if you didn't destroy them). However, Owlcat games don't collect stats.
I'm always thinking: Less but more unique would be so much more. It's easily what I personally dislike the most. No wonder that it's the chapter where you do all the detective work to look for the source of a disease in Kingmaker that I remember most fondly -- it was such a welcoming change in pace. Season Of The Bloom was it, I think.
