If there was perfect proxy for good people then $BIG_TECH would pay barrow of money for this.
10 years of experience says that person probably have seen a lot of software / projects / decisions and stuff.
Of course you could maintain one system for 10 years and struggle in new environment, but also there's difference between maintaining CRUD app for 10 years vs maintaining Linux kernel
For technical experience it's not a good indicator, for interpersonal experience it's spot on. It's easy to avoid doing anything technically difficult, but interpersonal situations arise unavoidably at a set rate, providing experience that you can't accelerate by having a weekend coding hobby.
Lots of questions are definitely for Senior level engineers or even devops, i.e. - "HTTP 2 vs HTTP 1.1". There is nothing useful for junior level developer to know the difference of such low level things. Anyway, junior engineer will have no chance to decide what HTTP protocol to use in his project in Apple.
Another example - "NodeJS event loop internals". Nothing useful for junior, senior level+ is assumed, if you want squeeze out of maximum performance from NodeJS V8.
>Lots of questions are definitely for Senior level engineers or even devops, i.e. - "HTTP 2 vs HTTP 1.1"
I think this kind of question just shows whether you're interested in web or not, because I bet that you could read differences between those two in 10min from some summary or RFCs.
Everything depends on how deep understanding between those two you had to show.
Even if you know differences between HTTP 1 and 2 it will not help you with web developement at all. In some rare cases web engineer can get performance boost for client to load data more quickly, but usually nobody cares about this.
Seniority comes mostly from experience 5/10 years
Of course some companies give senior titles for people with 2-3 years of xp, but I think we can all agree that this is big "XD"