At least the ones supported by GrapheneOS, so the Pixels, but I haven't really looked into it, so there may be more phones that do.

People who take security seriously do.
Just because you never had an issue doesn't mean there's no attack surface with an unlocked bootloader and root.
Due to the convenience I had rooted phones for years - without a single issue (that I was aware of).
Backup/restore of apps or phone, migration to a new phone is just so much easier with root unless you want to rely on 'Google cloud' for that.
But nowadays I value security more than convenience.