It may at one time have been possible to do both but i don’t think that it has ever been possible to be excellent at both. Not without the intellect of a Goethe or an Isaac Newton. I’ve never been interested in browser work but as a back end developer I work closely with front end developers and it’s very clear that we work in very different domains.

I may have to learn JS to stay in the remote-work domain (I’ll retire before I will work onsite ever again) but that will be for React, not browsers.