[webignition]

I'm full stack. I see what you're saying and I think that in some (many?) cases your impression is correct.

In my last job, I entered as a frontend developer and moved into more backend work in addition to frontend work. There was strong engineering vigour, rigorous code reviews and careful coding standards to ensure consistency. I'd like to think I was competent across the field and at least equal to my peers but that's not for me to judge. My peers and those to whom I reported were very pleased. This suggests externally-verified competency.

I find it better to enter as either a frontend developer or backend developer and then demonstrate internally competency at both rather than trying to sell yourself as full stack from the outset.

It helps to have been developing web-related software for the past 25 years. Over time you learn new things because they fascinate and interest you.

Recognisable competency throughout the stack is achievable by anyone with enough curiosity to explore combined with enough experience to know how little you actually know.