1. Use modfolders to add mods
2. it's a server side option to check and kick who doesn't have the exact same config
3. Use ArmA3 launcher to quickly enable/disable mods

/downvoted

1. I did. It doesn't matter.
2. Why should I use 3rd party software and relaunch game every time at all? It sounds like a kludge. And I'm tired of this arma 2 buggy shit with all these updaters that are taking hours to set up and never work properly.
3. It's not their business what other islands and mods I have for use on other servers. Imagine that CS servers would ban you for having any maps except one you're playing on. And you have to delete/move/disable all of them every time you enter another server. Just plain ridiculous. And that's what we have now.

You aren't forced to use 3rd party tools, you can do it from the game anyways !
Also, as server admin, i can assure you that allowing players to join your server with mods that are not needed can potentially lead to server instability (server "reads" every single pbo / bisign file you have loaded upon joining).

allowing players to join your server with mods that are not needed can potentially lead to server instability

Thanks, I didn't know that's the reason. I thought mods work independently and load only when necessary. Now it sounds having much more sense.