Nginx is now the most popular web server, overtaking Apache (opens in new tab)

You can proxy requests from nginx to backend application servers, but you cannot host those applications on the nginx.

Whereas with Apache2, PHP/Python/etc. interpreters can run directly in the Apache worker processes. Similarly, you can also run Nodejs/Ruby/Python web application as part of Apache with Passenger module.

I think both fpm and wsgi would fall under what OP called "proxying to application servers", despite using a different protocol. Yes it's technically "serving", but so is proxying and literally anything else a "server" does. Maybe "hosting" is a better term: both can serve any content, including dynamic, but apache can often host it as well (without an external server), which nginx can't do nearly as well.

shorter didn't mean clear that's the age old LoC fallacy

My advice as a fellow long-time Apache user who also went deep into nginx would be to look into Caddy.

For me, the main draw to nginx was powerful (web) proxying, static file performance and simpler configs - Caddy does all of that 10x. In a sense, nginx is right in between Apache and Caddy, so unless I need to proxy something obscure like RTMP or email, I rarely have a use for it these days.