Tbh, if you're already using rails the odds that you'll need svelte / react are pretty low. Sometimes you might, and those pages can pull those in, but generally speaking you can do a lot with Turbo and Stimulus.
I mean, it just totally depends on the application. It does add complexity, sure.
Turbo, stimulus, have their own pitfalls. I have worked with them a fair amount and have ran into headaches. Also, React has a massive community / ecosystem of ready made components, plugins, tutorials, etc. Turbo and stimulus are getting better on that front, but it is nowhere close, and many situations/patterns you have to figure out yourself.
Theres weird hate on React from a portion of the rails community that seems unwarranted. Probably because of some of DHH's commentary.