I worked at a startup that did this and it was... totally fine? Like, we hired a guy who knew how to set Kubernetes up, he spent like a week or two setting it up, and then it was totally solid and the development experience was great. I was building some of the core product-specific logic and it only made my life easier.

Which really just goes to show that the "legible" aspects matter far less than the illegible aspects. It's easy to say "hey, this startup is using boring technology and deploying a monolith, great!" or "Kubernetes and a bunch of services, over-complicated!". It's hard to say "hey, this startup's codebase is awful and it's an unforced error slowing them down" vs "hey, these guys are taking some shortcuts but it makes sense in context".

But a mess built on "boring", simple tech is going to derail you far more than a needlessly complex but well-executed setup.

Kubernetes is pretty ok if you keep things simple. The project I worked on had kubernetes set up years ago and from there on it just worked.