What if I don't change my Master Cylinder on a disc conversion?

Sorry guys I got ahead of myself. Pitched the factory prop valve and installed an adjustable prop valve when I swapped mc's. It really did work just fine though for 8 years the other way, no empty mc, no soft pedal, no locking rear brake issues. Although it's not optimal for good disc brakes, it will work fine and the emptying mc thing is just bull. If you can empty your mc in one stroke of the pedal, your brake system has real issues... If that were the case don't you think it would have happened to me at least once in 8 years? Like I said, I had zero safety issues, just didn't brake as weel as expected