Rails has a lot of "magic". Which is fine if you only hire veteran Rails developers who know the magic, but over time it becomes organizationally exhausting because ultimately you will have to train people, you will have people leave the org, and you'll have people coming from other orgs with way less conceptual overhead that keep asking "why don't we just..." to methodologies outside the core rails ecosystem.

Rails is perfectly fine but being perfectly fine is an unsatisfactory outcome over time.