Sleek black can be hard to come by. Sometimes you have to get help. This especially depends on your class/forms. The limited barrier locations are usually illusions.

Some foes just require full prep and you still aren't winning. If you're way over prepped for less dangerous foes, you're not going to kill them, because they will just flee. So, there's already an incentive to not over-prep. That's unless you can prevent them from getting away. Most characters who will be impacted by the ABS change you're proposing cannot stop someone from getting away.

I do find it ironic that after playing Bakrmarr, you think that ABS is a game balance issue. Bakrmarr with ABS was a game balance issue.

The chars who full prep for every fight will probably, when faced with not having ABS, just not fight.