Please see the HTML in http://www.geofrogger.net/review/esi.html as example.

Task: Require two words, that are not adjacent.

That's basically not a problem with regex, as long as they are on the same line. But try to search for "break" and "desire" in my example: Although these words appears on the page and in the same <p>, they are on different lines. The regex engine doesn't handle the line-breaks.

Workaround: Make multiple steps and require each separate

That's not elegant, as the result might be different on the second request. It's also getting harder to logically link your requirements.

Wish:

I'd love to have a GUI (and backend), where you can state multiple requires and logically link them.

Concerning the actual pattern matching problem: Probably the whole HTML could be "minified", i. e. all line-breaks removed; maybe other non-printing characters as well.

http://www.webinject.org/ roughly challenges the same problems and might serve as inspiration.