Super anecdotal, but I've seen a few instances of those in my time as sysadmin.
Whether it was just failed or malfunctioning updates, I can't tell, but I've had to deal with Windows not starting correctly after automatic updates multiple times.
Then there was the whole bricked HP laptop story recently, where automatic updates just randomly killed a lot of systems. We have multiple HP laptops in the company, though none were affected, but I can't say I wasn't sweating a little bit those days.
Backports are specifically tested for the purpose of being compatible with stable, so there should be no issues.
I can't really comment on what what gaming desktops need, I feel like you could absolutely play games without the latest drivers at all times, but I don't play any modern AAA games.
If you need bleeding edge software, then don't install Debian, for sure. Or go unstable with all the potential issues.
Technically, the title doesn't say "first", but yeah, kind of. :)