> I find that the main advantage of having less moving parts is that there's exponentially less things that can go wrong - and that makes reliability possible with very small teams

Right but it is a trade off to some degree. For us, to have ephemeral feature branches deployed to QA completely in a hands-off manner means we can do multiple releases per day as a small team. Most (almost all!) of the advantages we have seen from moving to a k8s infra have been DX, rather than UX.