There is this concept, especially in enterprise level architecture which is similar to a separation of concerns; basically that you use tools to solve a particu

There is this concept, especially in enterprise level architecture which is similar to a separation of concerns; basically that you use tools to solve a particular need. Sure, one could get by using the built-in caching of nginx or Apache httpd (version 2.4.x, which is just as performant as nginx), but when the cache becomes a bottleneck, and it WILL at some point when using a "does everything solution", you need something that simply does caching and does it WELL. Varnish will simply beat the pants off of nginx and httpd in head-to-head caching tests. Plus, the level of configurability in Varnish is again much, much better than what exists in nginx or httpd. It seems kind of nasty to say this, but nginx isn't the be all and end all. Now, yeah, you could say I'm biased, but this is because instead of being swayed by marketing, PR and FUD, I instead am swayed by real world scenarios. nginx is very, very good, but it is no longer heads-and-shoulders above httpd or anything else really. It is weird, and wrong, to take every other tool which does a part of what nginx does and immediately want to criticize it or say "nginx does that too! What do we need Foo for?!" When doing architecture, pick the right tools for the right job. And most of the time that means picking a caching layer, a TLS termination layer, dynamic content, Authn&Authz layer, etc...