Rails has bad spa suppott.
But Rails is hard to beat for CRUD apps.
I'm honestly surprised it didn't take off massively for internal enterprise CRUD stuff. It's by far the most productive stack I've ever used, the second closest being .NET w/ EntityFramework.
It was the darling of the early SaaS explosion of the early 2000s, and then just kind of died off in hype.
I like that it's opinionated, stops be from going down rabbit holes, and batteries included. There's nothing in the JS/TS framework of the day world that leaves me wondering "hmm, maybe I should stop using rails for this." It all seems worse, somehow, despite being more "modern."
All that extra complexity is great for the economy.
I struggled to explain I would now have to spend 4 hours updating dependencies, maintaining a node js pipeline and dealing with typescript all because you couldn't handle adding a new fucking single form input to a form with only 3 existing inputs, which would have taken only 3 lines of code between the HTML and C#. The cake was this is an intranet app where the entire form only gets used a few times a year at best.