I think you bring up some really good points. I think that DevOps is very team-centric and to some extent cross-team centric and removing that can make for an uneven environment.

I do think there are parts of it you can outsource such as first line on-call and I also think that DevOps as a service has a use case in a brand new start who maybe hasn't had time or needed to hire any DevOps personnel. But as a longer term play I think it runs contra to some of the ideas of DevOps.