These are all good point, that I think aren't really related to having devs do operations.

Having engineers understand what makes a service resilient and easy to manage, as well as giving them incentives to produce high quality code doesn't require them to do SRE. In particular, being close enough to the SRE team, getting inputs when building the feature, detailed feedback and requests on live services, and the blame when shit hits the fan, are a more scalable way of doing it IMHO.