Your question is essentially a proxy for server-side architectures and applications, not nodejs itself. It invites misrepresentation.
I feel like you guys think I asked them to rate themselves 1-5 on the subject. I did not, I got their resume, where they themselves rated them on the subject. With my question I was just checking whether that self-assessment was correct. I don't see how that is a bad question... Should I just believe their resume? Should I give them some programming assignments? Should I ask them to write a complex algo on a white board? I feel like just asking is a good way, personally, but maybe I'm wrong.
Asking them to self rate themselves is useless however, as their answer showed.
That's how I interpreted the comment and I'm pretty confident that's correct.
I ask for a 0 (never heard of it) to 10 (you made the thing or wrote a book on it) ranking and most people that have worked a couple years answer no higher than 5 or 6 but recent grads will say 8-9.
Pure anecdata but supports other comments about not knowing what you don’t know until you’ve been around different subjects for a bit.
Example: frontend design is self rated to a 6 but the person can not articulate the difference between raster and vector graphics (or doesn’t know what an SVG is or when to use one or not use one and vice versa).