I am baffled by the argument that's repeatedly advanced in different comment threads in this post: that php is easy for complete novices in web development to pick up, and that therefore... something. It reinforces the mindset that php is an entry-level language for amateurs; and if this is the case, then why would you want to keep using it for professional development once you are past your first web dev baby steps?
So with php is definitely possible to build large web apps as it is possible with other stacks. However compared to other languages with php it is very easy to get started as well as mainly the first dev setup is quite easy, although for professional work there might be no difference between the different stacks...
