And you keep your phone on during a film, and at the nice dinner, and during your daughter's wedding, and never go camping without phone service. That is exactly what is being described by "This answer always downplays what "on call" really means."
During your rotation, you have to have your phone with you. I go to the movies and to nice dinners. I would definitely get my rotation covered for a wedding or camping.
You should have faith in the systems that you build. If you don't want to carry a pager for them, why does someone else want to do it?
This is why SRE organizations typically have stringent requirements for stability before accepting a rotation, and will give it back if reliability drops below a certain level.
SREs have global responsibility to the system and have a correspondingly global view. If your system broke down because of a bug you wrote, that’s on you. If a system three times removed from yours that you didn’t know depended on you broke because you changed a non-API behavior, that’s where SREs shine: they know how to quickly isolate the problem, roll back the necessary systems, and define how to avoid similar problems in the future.
Expecting another group to maintain your code seems an awful lot like throwing it over the wall.