Comment by crabbone

Precisely.

This also reminded me, I think in the PHP 3 era, PHP used to "sanitize" the contents of URL requests to blanket combat SQL injections, or perhaps, it was a configuration setting that would be frequently turned on in shared hosting services. This, of course, would've been very soon discovered by the authors of the PHP site and various techniques were employed to circumvent this restriction, overall giving probably even worse outcomes than if the "sanitation" wasn't there to begin with.