That other guy is an idiot
So, in conclusion:
1.) Someone wrote a piece of upload code, that allows people to easily upload anything to a server, including executable .php files.
And the piece of the code that prevented any uploaded php to be executed, was in a .htaccess-file.
...and no one would be stupid enough to blindly fuck with the .htaccess-file to mess up security.
So we're all good here, right?
2.) Someone made a nice little improvement in the server-code, that turned off the use of .htaccess-files.
See, it all runs a little faster now!
...and no one would be stupid enough to just let anyone upload .php-files to to your server anyway.
So we're all good here, right?
3.) Everyone and their uncle put the upload-code on servers running the server-code, and then updated the server-code with the fix, that makes it run little faster.
And no worries, because we're all good here, right?
...
A little time passed...
And then the world imploded, and the moon flew off into space.
And whos fault is it?
(All together now)
THE OTHER GUY!
(Or maybe jQuery? somehow? idk...)