That's a good point I don't see mentioned much about choice of tech stack and impact on career. It's not so much about the technical merits of the stack itself

That's a good point I don't see mentioned much about choice of tech stack and impact on career. It's not so much about the technical merits of the stack itself as about what kinds of companies and projects use that stack, and sometimes it might be worth learning some technologies you might not be particularly invested in if you want to work at those companies. It's not easy to switch stacks either - yes you can learn a new stack but you need those golden "years of experience" in your resume, making a switch an expensive and risky proposition, so you need to choose wisely.