You know, I think I do it as much as ever -- it's just so much easier in 3E.
"You want to push him off the cliff? Okay, um, opposed strength checks." I mean, AD&D didn't even have a mechanic to do that with.
I don't really know the 3E rules. I just know the principle. Push off cliff -- opposed strength checks, maybe a bonus for somebody extra stable, probably an AoO on the way in, ta-da! Oh, wait, that's a Bull Rush. But I don't need to remember the rules for Bull Rush (and indeed I don't) -- I just put it together using my common sense and the basic ideas of the game and lo and behold I get a useful, easy to manage mechanic that turns out reasonable results.
One of the things I really like about 3E is how... "squishy" it is. I mean, I can sqooze it and squeeze it into all sort of odd shapes and it still pretty much works okay. I don't need to know dozens of rules, just a few principles that hold it all together. I can wing the rest.