Without more details it's hard to say, but it sounds like this wasn't so much an RB environs-specific accident, per se, as one of some sort of technical oversight typical of rappelling accidents. That said, there can be plenty of distractions out there.
In the end though, RB is what it is. It's home to a number of fine lines, but in a problematic setting and with serious safety issues. Then again, pretty much any crag you approach and setup on from the top should set off automatic warning signals in your head; add slick-as-snot soil conditions and you have a very dangerous place.
I think many folks seriously underestimate the place because it's a short, innocuous, urban 'practice' crag - don't be one of them - be on your guard and extremely careful at all times out there.