I have literally never seen anyone use PHP for something that was not a website

You don't get out and about often do you? PHP has an excellent CLI facilitating easy production of shell scripts.

aside from its actual technical merits or shortcomings, most programmers worth their salt would really rather not be using PHP

Please cite real studies done that back up this opinion. Thanks. Just because you say it's so, doesn't make it so.

Science has, arguably, improved our lives in very real and very practical ways. It's a bit harder to make that case for philosophy.

That's the problem with not being able to see outside of our reality. If our reality was just turned on a second before you made that statement, then for all considerations of our existence, science is at the exact same stage it was when you popped into existence with a complete repertoire of conjured memories. Consider what happens when you boot up a game and everything is pre-oriented as the game was staged. So too may be true for reality. Given that argument, maybe science has done nothing for us ;)