That hasn't been my experience in the last decade or so, and new people or people with different specialisations are indeed unlikely to be good at everything on

That hasn't been my experience in the last decade or so, and new people or people with different specialisations are indeed unlikely to be good at everything on the first day. Before the overlap between development and operations there were multiple teams involved in every step, everything was slow and expensive and you'd be lucky to deploy once a week. After making sure that where overlap exists the people that have the skills to work in that area can do what they need to do (i.e. build, verify, release and instrument the systems they are responsible for) we get every team releasing every system multiple times per day in small increments. This is both faster, easier for everyone, and worth the ROI on people and tech far more than trying to invent borders and fiefdoms between hyper-specialised teams.