The rap is that PHP is very easy to embed in HTML and it has a reputation of being "easier" for non-programmers to use. Whether or not that's true is up for interpretation, but that's the rap.

One example that I'm extrapolating is MacWorld.com because it's listed as a Bricolage site but has some deeper pages (like this one) with PHP extensions. Extensions don't mean much because you can tweak apache to do whatever you want, but that's my theory and I'm sticking to it.