If you have enough talent that a good quality Stripe integration takes only a day to write, bending Rails or Laravel to serve websockets is not going to take more than a few days to write either. The true pain of non-standard languages is not in having to implement any specific dependency yourself but in having to reimplement a few dozen trivial-but-not-easy things yourself. It's a death by a hundred small cuts.

On the one hand u r writing a wrapper over an already well specified rest api of stripe and on the other hand u need to modify a programming language runtime to be faster and reliable for real time operations. I'm not sure these tasks are really comparable in any way.

Choosing non-popular languages is a trade off yes but not as much as people think especially if you have a good team willing to learn them.

There are also benefits apart from technical ones like better job retention and attracting finer talent without having to filter hundreds of resumes. I will say if your business is made around hiring and making anyone work of the shelf then it's a bad idea.