Everything at web scale is embarrassingly parallel, at least on some fronts. There's still often the bottleneck of maintaining state (in a database, probably), but a heavily loaded server will have hundreds or thousands of processes or threads or some kind of async (probably epoll or something reasonably efficient on modern systems) to serve many clients. Which is why Erlang (and Elixir) has some very enthusiastic proponents.

Serving the web is, I think, a very big part of the "general computing" space, today.