......Because MS didn't program it in, that's why

I can think of a few legitimate reasons why ATC was not programed into MP.

First off, having AI aircraft in MP could lead to a few problems. Not everyone has the default traffic, or wants to keep it at 100% due to system performances.

If someone with only default traffic were to play MP with someone who only had PAI traffic, and unless it was over a fast LAN or a DSL, there wouldn't be enough bandwidth to transfer AI models, and routes; Or the first computer would only see his AI traffic while the second computer saw only PAI traffic. This could lead to some confusion

There just wouldn't be enough bandwith to have an AI ATC system interacting with just two computers, (let alone several), not to mention AI models, routes, and even bgl files being transferred.

For me, there's already enough lag as it is while playing online

What if the first computer had stock scenery, while the second computer had addon afcad files for different airports. I can think of several additional problems that that alone could cause.

??? Excuse a Newbie - what is "MP" ???