At a certain point, asking the question repeatedly and not accepting any answer becomes
sealioning after a while. I've explained why I do what I do and it seems that no amount of explanation will suffice. The only other thing I can point out is that while I'm good at extemporaneous creativity, a lot of people are not. Put them on the spot and ask them to describe the person they're talking to and it will be incredibly stressful and unfun.
The immersion factor applies to both DM and player for me. As a DM I'm immersing myself in the world, picturing it and figuring out how the different pieces are interacting and how they're going to respond to what the players say and do. Yes, sometimes I'll fill in the picture a bit based on players asking questions, but that's different from players regularly adding to the picture and then trying to figure out how to add it in. Especially now because I have to figure out what it is exactly they're adding. Is there a band? If I add it, I can decide certain details as needed and riff off of it. If the player does it, is it a bluegrass band? Jazz equivalent? Perhaps a sultry lounge singer? Or are we going with Renaissance Festival folk music? Now it's 20 questions to the player, it's just flipping who needs to add details. I can't just run with my image of the band and characterizations of the band members, I have to fit it to the player's imagination. Maybe I imagine a Willie Nelson as main singer and they're envisioning ye' old version of Taylor Swift.
As a player I want to focus on my character, what they're thinking and feeling. I want to experience the world not create it.
But it really comes down to an agreement on what game we're playing. I can't explain why I like the standard style of D&D other than "it's a preference" any more than I can explain why I prefer the taste of whole wheat bread to white, I just like the flavor better. Why do I put grape jelly on my toast instead of strawberry? Because it's a preference. We like what we like and sometimes there's no deeper meaning.