Can’t speak for OP, but there are a lot of things people do out there, not just web apps. People building games, robots, trading systems, distributed databases

Can’t speak for OP, but there are a lot of things people do out there, not just web apps. People building games, robots, trading systems, distributed databases, CDNs, etc could be really limited in their capability if they didn’t grok networking concepts on a deeper level. It also tends to tie in heavily to other systems concepts (things like zero-copy, or even basic elements like ring buffers). I think you might also underestimate just how little knowledge a lot of people have. You went to a legit uni and took a legit course. The interview question OP asks is an old favourite I used to ask too. A lot of people answered something like “clicky-linky-page-rendery!” So a bit of education on the many layers below that doesn’t hurt.