Fix Your Tanks Damage Please

Just got out of a ranked game where I was playing Katarina mid lane against a Zac mid lane (I know lmao). I almost had my gunblade (hex-rev & cutlass) and I did a full e,w,e,q,e (ult was down) with an electrocute proc and Zac does his e,w,q with electrocute and did 3/4 of my health. The only items he had were boots of speed, Doran's shield, and a Spectre's Cowl. Now I get some champs do damage based on health but there is no reason a tank should out damage an assassin if they build tank. Please make tanks do less damage or make them less tanky if they will do damage. I had a Rammus in the same game 4 shot me with a q, taunt, and 3 autos (i auto'd twice or three times before I died) and he also built full tank. The game isn't fun anymore for assassins and other squishies when you have full tanks out damaging them.