[suneilp]

It seems like you're making the assumption that 'they' would choose nginx just because it's superior.

There are many reasons for them not to go with nginx. The biggest one is probably that it's just different. Managing it is different. Configuring it is different (regardless of any similarities). Testing is still required.

It's nothing new that a lot of people either want to be lazy or are afraid of taking risks.

Being 'better' alone isn't a good enough reason to expect everyone to switch.

[fennecfoxen]

Different is risky. Consider, for example, lighttpd, another lightweight Apache alternative. It was chosen for a certain project at a former workplace of mine. Not too very long afterward, significant problems with memory leaks started occurring on the deployments that used it, and I found myself tasked with fixing them.

I was unprepared and somewhat astounded to find that lighttpd does not support sending "large files" over CGI, FastCGI, or proxy connections, and the maintainers don't care (cf. http://redmine.lighttpd.net/issues/1283 ...)

Besides the waste of engineering time, customers were impacted.