It runs everywhere because it's really old and popular. So you could just call it momentum. I for one would never choose technology based on momentum alone. An

It runs everywhere because it's really old and popular. So you could just call it momentum. I for one would never choose technology based on momentum alone. And you might get PHP running in almost all servers, but that says nothing about all your dependencies such as mail servers, message queues and the like. So the fact that it runs everywhere doesn't actually mean that much.