Kits require stock . That's the first problem.
Locally they had been running a cash back offer. Buy the camera and a lens of your choice and get money back. IMHO better than a kit since you got to pick virtually any lens. Better for them since they didn't have to create a kit SKU and deal with the stock issues.
The other issue is at the R5 level many buyers already have lenses or wouldn't want the kit lens. That's why the R6 offers a kit and not the R5.
If they're assuming an R5 buyer will already have an RF 24-105 f/4 L, they were certainly mistaken in my case. But they did offer that kit, so I don't think they were assuming that.
But I agree the kits don't offer as much flexibility as "get cash back if you buy a camera with any lens" offers would.
When the M6-II came out, I wanted the camera and the detachable view finder. But there was no kit like that. There was camera + viewfinder + one of two different lenses, of which I had one of them from a previous kit purchase of an M50 (and never use, now that I have the Tamron 18-200) or another lens (which would also be superfluous for the same reason).
I'm reliably told the Canon people were asked at a pre-release event why they didn't have camera+viewfinder as a kit, and Canon just ignored the question. So I bought the kit and sold the lens, which is exactly what Canon claims they DON'T want people doing. But they left me with no real alternative because of the choice they made. I'd never have done it if I could have simply bought camera + viewfinder as a kit.