Chainsaw's Instant Kill should be removed

[Absurdity]

while the sam for example is very common that when you are the last one in crystal someone WILL have to hit you and they get the debuff, easy 100% chance kill, can even happen literally every match if the sam is being sneaky, while the chainsaw kill? lol once every 10 to probably 20 match.. so?

No you don't. If you can't keep yourself from hitting the SAM for 5 seconds ,which is the duration of Chiten, then that's entirely on you.