The issue is that you either go full damage and the game is trivially easy to the point you immediately delete any enemy that shows up, or you don't, and some glaring issues start to show up. Have you tried a full mobility playstyle or a mixed playstyle that doesn't maximize raw damage output? The TTK becomes extremely awkward, and the mobility you gain doesn't make up for the damage and range you lose. This is why it's a balance issue and why it would be troublesome and lenghty to finetune with a penalty system.