Just check certain ban requests and you see why. People sometimes respec in the middle of the round and spawn naked the next round because they use gear that has difficulty requirements, and some of them get tked for that, get reported for that or even banned for that.
This could be an idea to stop anyone from intenional leeching or just spawning naked after respec.
It doesn't even has to be the minimum armor, maybe just forcing someone to spawn with a weapon would be enough (as it is in the rules anyway).