If people build zero defense
Why is it asinine to them that they can be killed by someone who builds no damage, or even a single damage item?
Someone with a full tank build shouldn't be able to do like 500 total damage lategame to an ADC with like 70 armor or 40 mr, tops. You're building LITERALLY NO DEFENSE, so even though you get armor/mr/hp per level, we all also get damage per level and our skills start to hit harder.
Now consider that some tanks WILL build damage, like RoA on Maokai, and it's just one more reason you SHOULD be able to get chunked out from a tank's full rotation.

for tankyness...... AND offense [slayer-jinx-unamused]
and hextech gunblade gives sustain, these items are just way too op and all for tanks .-.
and 
(Exception for Malphite against full ad)
should be heavily reworked or removed. Since it doesn't really help juggernauts, and breaks a bunch of other champs. As fun as Righteous glory, Deadman's Plate, Predator Cho is, I can see why people would be frustrated by it.