Because of this, recently I started wondering about why only PHP has succeeded in this area, given that there are plenty of other tech stacks that could work in a similar configuration. Why are there seemingly no (or very few) options for the likes of Ruby, Python, .NET, Java or any other set of technologies?
Is it because they've traditionally been deployed as separte apps? What would prevent someone from offering shared Tomcat instances with some clever load balancing and routing added? Or is it because many of those are comparatively more heavyweight than the CGI-like approach of PHP? Or maybe it has something to do with them needing native dependencies in some cases (which I've seen for Ruby and PHP, thus necessitating certain other packages on the host as well)? Or perhaps it's more a sign of the times and there's not as much reason to attempt to enter the niche which PHP already covers, given the necessary engineering effort for getting somewhat secure shared hosting up and running?
Any thoughts?
These days it's probably simpler to offer virtualized servers than shared hosting for anyone who wants to use something else, so there's no reason to change.
I get the impression that companies like Heroku came about because the established shared hosting companies were too slow to adapt when Ruby on Rails exploded in popularity.