I don't think this is true - while exposure to a wider or narrower set of these domains / technologies will depend greatly by your held positions and responsibilities within teams, size of companies worked for, and raw years of experience (so it is a gradient), I would expect from an experienced web developer to simply be very familiar with all of these if they are passionate and curious about what they do.
I consider myself a mediocre senior web dev, and I am can humbly say that I'm very familiar with all of the listed, without intentional effort in that direction over the years, simply because I wanted to understand the context of some of the things I needed to do, and also poke into each enough to understand how much depth there is and what I don't know. It is natural that it tends to add up.
Over the years, I saw a strong correlation between that breadth and how "good" someone was - on the example of someone working on the fronted in a team, I see 3 basic categories:
1) Not very good: I can do only the most direct and specified things and if something doesn't go as implementation plan intended, or requires outside of what I see as my "formal scope" (e.g. "frontend developer", so React + CSS), I expect someone to solve it so I can continue
2) Ok, but limited: I do only the things inside my "formal scope", so if I'm building a frontend to a web app, it's someone else's responsibility to think about e.g. security - but when something doesn't go as planned along my line of work, I'll find why and unblock it
3) Good: We're building a web app, what are all the things it needs to consider and achieve? My part in the team is this UI / frontend, but if security is important for this use-case, how will my frontend be cognizant of the security goals? I should read up that OSI thing I heard about, cover the basics on my side, and start the discussion on it so we as a team ensure the frontend part is good security-wise
> I wanted to understand the context of some of the things I needed to do, and also poke into each enough to understand how much depth there is and what I don't know
To me this is not equivalent to "very familiar". I think whakim's comment puts things well:
> I use AWS day-to-day, but haven't used GCP day-to-day in 5+ years - should I realistically be able to keep abreast of the vast number of GCP changes that have happened over that time (plus all the changes in devops that make the workflows I was using 10 years ago look outdated)? Many projects don't need Websockets or Eventsource - do I have to keep that knowledge top-of-mind across the years that I don't use them? Can you really claim that you're "very familiar" with that web framework that you used two jobs ago - assuming there haven't been a bunch of major changes since then?
I consider myself a mediocre senior web dev, and I am can humbly say that I'm very familiar with all of the listed, without intentional effort in that direction over the years, simply because I wanted to understand the context of some of the things I needed to do, and also poke into each enough to understand how much depth there is and what I don't know. It is natural that it tends to add up.
Over the years, I saw a strong correlation between that breadth and how "good" someone was - on the example of someone working on the fronted in a team, I see 3 basic categories:
1) Not very good: I can do only the most direct and specified things and if something doesn't go as implementation plan intended, or requires outside of what I see as my "formal scope" (e.g. "frontend developer", so React + CSS), I expect someone to solve it so I can continue
2) Ok, but limited: I do only the things inside my "formal scope", so if I'm building a frontend to a web app, it's someone else's responsibility to think about e.g. security - but when something doesn't go as planned along my line of work, I'll find why and unblock it
3) Good: We're building a web app, what are all the things it needs to consider and achieve? My part in the team is this UI / frontend, but if security is important for this use-case, how will my frontend be cognizant of the security goals? I should read up that OSI thing I heard about, cover the basics on my side, and start the discussion on it so we as a team ensure the frontend part is good security-wise