There are more hacks than just kill aura, though. Hacking is hacking. If someone is hacking, they're giving themselves an unfair advantage over those who do not use hacked clients. It doesn't matter if this advantage will improve your progress on parkour, or the armor you have on prison.
I'll be honest with you, my kill aura and anti knock back on OP PvP earlier worked fine. I was 1v1ing my friend and for the lols I decided to hack.
There actually is parkour hack that makes you automatically jump when you reach the end of a block :/ Dont know how well it works but its still a thing.