It's not just ease of installation by sysadmins, but ease of use on shared hosting and ease of script installation by non-developers.
I can walk my mother through installation of a PHP script. I can almost walk her through installation of a CGI script in any language, really. But unless that shared host has already set up a Python or Ruby environment (few do; I can count the ones I know on my left hand), I'd never, ever dream of trying to walk her through setting up something in other languages.
Making running scripts as easy as dropping them onto a filesystem would be perhaps the killer feature for other languages to target, if they want to take a bite out of PHP's consumer market share.
Of course, then there's another battle: shared hosting providers. The vast majority are running some sort of third-party control panel software with very opinionated hooks deep into every bit of configuration on the machine. Unless that killer feature can be baked into that software, and unless the shared host actually updates their software, there's no hope.
You wouldn't believe how many shared hosts are running ten+ year old installations of everything, not giving a crap that they're out of date. And hey, that ten year old version of PHP still installed there is still going to work just fine with the majority of scripts...
I can walk my mother through installation of a PHP script. I can almost walk her through installation of a CGI script in any language, really. But unless that shared host has already set up a Python or Ruby environment (few do; I can count the ones I know on my left hand), I'd never, ever dream of trying to walk her through setting up something in other languages.
Making running scripts as easy as dropping them onto a filesystem would be perhaps the killer feature for other languages to target, if they want to take a bite out of PHP's consumer market share.
Of course, then there's another battle: shared hosting providers. The vast majority are running some sort of third-party control panel software with very opinionated hooks deep into every bit of configuration on the machine. Unless that killer feature can be baked into that software, and unless the shared host actually updates their software, there's no hope.
You wouldn't believe how many shared hosts are running ten+ year old installations of everything, not giving a crap that they're out of date. And hey, that ten year old version of PHP still installed there is still going to work just fine with the majority of scripts...