I agree with what you say on principles, the challenge is doing it in the real world with real people and real organizations.
You're practically saying that the tech lead and manager are on call 24/7 because they can be called anytime. Are they okay with that? can they actually do something about the pages/runbooks? (in many organizations it's not that simple).
What's the average tenure in tech? Something like a year (you can surely imagine that it gets shorter with bad oncall). You're constantly having new joiners (and leavers). It's not as simple as there being 6 people at the ready at all times.
Practically the team starts from zero and have to ramp up to 6 members, how easy is it to recruit 6 dev/ops/sre? It's not that easy and it takes a lot of time and they leave. Outside of a few large organization, teams/department might never reach the size where on call is bearable.
You're practically saying that the tech lead and manager are on call 24/7 because they can be called anytime. Are they okay with that? can they actually do something about the pages/runbooks? (in many organizations it's not that simple).
What's the average tenure in tech? Something like a year (you can surely imagine that it gets shorter with bad oncall). You're constantly having new joiners (and leavers). It's not as simple as there being 6 people at the ready at all times.
Practically the team starts from zero and have to ramp up to 6 members, how easy is it to recruit 6 dev/ops/sre? It's not that easy and it takes a lot of time and they leave. Outside of a few large organization, teams/department might never reach the size where on call is bearable.