Don't forget the other half of the web development stack: Javascript. The absolute worst scripting language ever desi--well no, it wasn't designed, it just kind of happened accidentally. At least PHP solved a problem of the day, Javascript was nonsense from the start, and somehow managed to become critical infrastructure.
While yes, PHP begun as a collection of macros and was never intended to be a programming language, JS was made by someone with intention. To quote from wiki,
> [Eich] originally joined intending to put Scheme "in the browser", but his Netscape managers insisted that the language's syntax resemble that of Java. As a result, Eich devised a language that had much of the functionality of Scheme, the object-orientation of Self, and the syntax of Java.
I've seen quotes before from Eich himself I believe that he was combining these influences at the time - Scheme's closures, Self's prototypes. It didn't "just happen".