On the opposite end of the spectrum, if your stack is too old (and niche enough) then you won't get to know it very well once every bit of documentation was hosted on expired domain name, and you can only find bits of online discussion about it are Internet Archives snapshots of a forum long since dead.

And also you don't get to integrate it very well if everything around it isn't maintained, and compatible on old version of a library (with said documentation not existing anymore).

Also, while resume-driven development is not a good thing either, it's certainly not a good investment to pigeonhole your career into working with something you hate working with.