The issue I was facing in a previous life was the turnover. We had data scientists, DBA and many specialized roles stay pretty long, where devops moved away at about twice the rate, and work life balance was mentionned in many exit interviews.
I agree with you that it's extremely formative, and having devs involved basically from start to end of the service surface gives a lot of flexibility. The downside being that it requires a ton of different skills as well, and while people learn, many won't get comfortable with it even after months.
This makes it specially tough when people get called at 3 in the morning to deal with an emergency while they've already spent half the night sleep deprived from their kid puking all night. The worst part being that while people could understand wanting to skip turn one or two times, engineers with small kids will have enough going in their lives that most on-call instances land at a time they're busy dealing with more important matters.