Why don't astro cards stack?

[HyoMinPark]

if they would be OP then they should be rebalanced. this isn't a very good response. it's bad multiplayer design to allow 2 players to override eachothers benefits. that should not happen. everyone should be able to use their full capabilities with each other without worry that they'll screw each other over. and i didn't ask about AST regens and WHM regens. i'm asking if a WHM puts a regen on someone and a second WHM puts the same regen on the same character do they stack? BECAUSE THEY SHOULD

Overwriting cards can be easily avoided if you just communicate with your co-AST. It’s not that difficult to do.

Despite the cards not stacking, back in Creator there were speedkills done with double AST when Balance was +20% for single target and +10% for AOE.

WHM regens stack with one another—you can have double Regens and double Medica II HoTs.