D:OS 1 was fine. But multiplayer does take extra time and resources to work on. Multiplayer might force the devs to not include shortcuts, but shortcuts can save time. There is the claim that "having to take into account the multiplayer means ensuring that all kinds of reactivity works properly". Okay, but what if you turn that around. What would prevent the devs from putting that kind of reactivity into a single-player-only game?
D:OS 2 also has a stronger multiplayer focus than D:OS 1, with its competitive questing, arena fighting, and they also proposed the definitely-only-multiplayer DM mode. The arena fighting could be useful in single-player as free income if the winner gets a prize, but the others are definitely multiplayer only.
So I don't really accept the claim that adding a lot of multiplayer focus ONLY improves single-player gameplay. There are still trade-offs.
I didn't say that I would hate a turn-based Divinity 3. I just said that I would not MIND if it was real-time.
I could easily see Larian continuing on with D:OS 3 and 4 in the same vein as D:OS 1 and D:OS 2. That doesn't mean that they have to use the same style for Divinity 3 as they would for D:OS 3.