PHP has more ubiquity, so it's a least common denominator sort of thing. You can find tons of hosts running a LAMP stack, but not so many supporting Ruby. That

PHP has more ubiquity, so it's a least common denominator sort of thing. You can find tons of hosts running a LAMP stack, but not so many supporting Ruby. That is mainly because the tooling needed to maintain a Ruby application server has some additional complexity over PHP, which is mostly plug-and-play. Passenger helps a lot with that, but it's nowhere near the distribution level of PHP, so that is restricting the ecosystem currently. Basically, most people looking to setup a WordPress install can't deal with even the simplest CLI. So things like Heroku or a one-click Digital Ocean box are out. This could be a good idea for a startup...