I wonder why we still don't have a simple standard way of dealing with abusive http-traffic, like RBL's for mail. Way to often have I seen systems getting over

I wonder why we still don't have a simple standard way of dealing with abusive http-traffic, like RBL's for mail. Way to often have I seen systems getting overrun with rogue traffic, usually spam-bots and vulnerability scanners, and lots of small sites get into serious trouble because of this.