Been working with Rails close to a decade now. I've built several, non-trivial products using Rails for the API, by myself. What I and my coworkers dislike about Rails is the sheer amount of magic. Oh and concerns, let's not forget that pattern.
Rails is amazing at standing up a CRUD app (really API) in a matter of minutes. I can have a basic CRUD app with authentication, authorization, API, caching, background jobs, local development (docker compose), production in any cloud / k8s and CI/CD done within a day. Adding business logic that's well tested is simple.
Once the app starts to get serious usage, needs to integrate with complex enterprise systems, handle huge loads of data, etc. it becomes necessary to step away from Rails-way of doing things. All of a sudden you can't push more into Sidekiq cause of how much it impacts the DB via ORM loading. Now you're writing custom SQL. It's not all that hard to do in Rails, but at that point, you're writing Ruby and not using Rails magic any more.
Your dismissive comment does not address the realities of building a solution that goes beyond CRUD. It ignores the many levels of experience present on a team or the amount of technical debt one accrues while building a non-trivial production system.
While it doesn't take much experience to get started with Rails or to get a good amount of progress on a product, it takes skill to keep the technical debt under control. Or to make good decisions about architecture. Or to understand which parts of the system to optimize. It requires actual experience building web solutions without the crutch of a framework to know when to ignore Rails and when to double-down on it.