I feel that having a specialism is more a more marketable headline early on in your career (e.g. I am a React Developer). As you become more senior the expectat

I feel that having a specialism is more a more marketable headline early on in your career (e.g. I am a React Developer). As you become more senior the expectation is for you to take on additional roles such as hiring, coaching and mentoring. This is very hard if you have focused to much on one area and not taken a more general view. But this is all about what you want from your career. Some people strive for leadership roles (CTO/Tech Lead) and some people prefer to write code (Senior Developer). Both careers are valid options.