So i have seen players with spy going 6/8 blocks while invisible, its hard for me to find them. So if you can make it 3 blocks when ur invis
It's already hard enough to infiltrate enemy bases using spy with the 6/8 block unvanish bug. 3 blocks would be silly, since you can't to much except avoid combat. Players would almost always prefer assassin over it and it would never get played. Either way, you can still spam attack and hit invis spies, just like the good old tf2 days of defending your turret from spies as an engineer :3 Having to sneak and move slower is already a good enough drawback.