RG's comments that only incompetent parties knock rocks down seems exaggerated.
When I was guiding, I somehow managed, many many times, to take one or two total beginners on Easy O, belay them up to the top with all the piles of rope and other things that have to be managed, coil up the ropes and change from climbing shoes to walking shoes, and never have them or me roll so much as a tiny pebble over the edge.
If a guide and two rank beginners can manage this over and over again, then you're incompetent if you are knocking stuff over, I don't care how long you've been climbing and what elevated grades you crush.
Maybe we need an evening guide's clinic on how to pay attention to what the hell you are doing? It ain't rocket science.
But this is just a grouchy old rant. It is abundantly clear that we can't get climbers, apparently even "strong experienced" ones, to pay attention to what the hell they are doing. The only way to deal with this general incompetence is to either keep an anchor below the top or else work on the top to make it safe for the distracted masses.
RG's comments about putting an anchor to the side seems good (so people don't rap the climb), but people will then make a directional at the current anchor if they can. And it would mean establishing another anchor - heavens!
Heavens indeed---that's not what was proposing, which was to eliminate
the current anchor and replace it
with one over Hether (if the cracks for doing so are there).