"they actually thought they had addressed the cheating issue initially by making any modified pk3 files unusable on servers that ran "pure"..."
that has been around sense the q3 engine came out, but it wasn't enough for q3 or any game sense then so it makes no sense that it should be any different for cod.
"ut this also makes it impossible to place user maps in your main folder and join a pure server"
so not only did they fail to see the need for more cheat protection but they also borked q3's built in cheat protection? nice.
"(as well as the issue of not being able to place more than 4 or 5 maps at a time in your main , and still run stable )"
let me guess, they have all their assests spread out over a huge number of .pk3 files so just 4 or 5 maps pushes you over the built in limit?