I think this fear is not entirely wrong, but is significantly overblown. There's a significant gap between what job descriptions ask for and what companies will

I think this fear is not entirely wrong, but is significantly overblown. There's a significant gap between what job descriptions ask for and what companies will actually hire. A resume full of dead technology isn't going to help you ladder your way up to bigger and higher-paying roles, but it's also not going to make you unemployable. A resume full of less-shiny but still relevant technologies, otoh, has a lot of potential. You have fewer places to look for jobs, but you're a lot more exciting to the places which do want your skills.