it is a pain in the ass to multi.
My solution is thus. 1 char online per unique ip. Every char online must have a unique ip. If you can amass 100 unique ips, and play 100 chars at once, power to you. If you want imms/staff to police the mortal playerbase, then guess what, this new admin staff is not going to be any better than the last admin staff.
The real issue is, people are so attached to their shinies and characters that they are afraid to die now and fear pk.
People speak of various doomsday scenarios like 40 level 1 bots camped outside the inn ready to thornspray you to death. But the reality is, controlling more than 3 chars at once is very hard and tedious unless you have some sophisticated scripts. Your average assist bot won't do the trick. And any bot group will lose in any large scale pk. I can point to numerous pk logs I've seen from the bot perspective. Bots are hard to ambush but easy to pk. And bots are not creative like human pk'ers can be.
The reason why most folks have suggested an arbitrary number of 2 bots per group or whatever is because that's what they have experience playing with and controlling. The reality is once you scale to 5 chars or 8 chars at once, it's pretty hard without sophisticated scripts and programs which is why you don't see armies of bots running around today. Only PoG maybe in years past, and they never fought straight up 10v10.