If you really have a competitive gaming brain, then you wouldn’t be so upset right now because all of this information is fairly obvious.
Snipers will never OHKO any hero on offense without some form of team support. Snipers are meant to finish off an enemy but you can’t be expecting to do 1,000 damage unless you have some buffs and ailments on the field, hence why heroes like Panther, Eve, Frida, etc. are so valuable. Most KO’s are done in a 1-2 punch format.
Personally, I am not a big fan of using snipers as I tend to play the stall game with bulky heroes who use buffs/ailments to strengthen allies and weaken enemies and then use DoT/AoE heroes to decimate all the heroes at once rather than take out one at a time.
But if you can’t figure out how to competitively take advantage of using someone like Sartana, then I think you are highly overestimating your cOmPeTitIvE gAmEr bRaIn