The MP concept is not the problem. You need not use it, if you want not to send variable or entity updates, just send packets and dont send variables and switch off entity updates. But for beginners starting with MP, the concept is good.

I think what's lacking was encryption/security that seems implemented now, and then server to server communication. Updating only clients in range is not necessary I think because I'm with Excessus here, this can be programmed by the user.