I was playing Nasus had 300 armor without ult and a thornmail, yet Caitlyn still hit me for 450 each shot non-crit. What's the point of even buying armor? Thornmail didn't even damage her cause she was healing for more than it was doing.
This is what I have been saying but people don't seem to understand that armor is way to easily and effectively countered in the game currently
I'm really curious how you had "300 armor without ult" with
?
base armor at 18 = 84.4
armor from items = 130
armor from runes = 13.2
armor from masteries = +5% bonus armor (7.2)
total = 234.8.
Also I'm curious why you bought a thornmail over randuin's.
And how you think caitlyn with
could hit for 450 damage through a minimum of 105 effective armor with non crits.
You had thornmail, a ninja tabi and armor runes. That means 100+30+4+9+85 (from base armor) = 228. That's nowhere near 300 armor. Cait had around 340 AD, plus armor shredding from black cleaver, plus 45% armor penetration from LDR. Even if she were dealing true damage (which she wasn't), it still wouldn't be 450 damage without criting, though she still would hurt alot. But that doesn't come without a price, she invested a lot to do all that and had no resistances at all apart from her runes, so she was rather squishy. If she managed to actually AA several times for the black cleaver to stack without being killed, she either positioned flawlessly, her team peeled for her flawlessly, or your team failed to target her. Either way, they deserve to be rewarded for playing well, or your team deserved to be punished for not being up to the par.
Nothing wrong happened, you and your team were just outplayed. It happens, accept it, learn from it, and take the lesson to the next. Shifting the blame onto the game instead is the worst you can do, because you'll never improve with that attitude.
450 a shot non-crit? Were they headshots?
Otherwise she must have had about a good 700 AD lol
its so that once you start building armor lategame rather than earlygame you can more effectively spend your defense gold.
If you buy it early it will just get penetrated, if you get hp instead then all they'll have to shred that is some % hp items and abilities with kindof gated usage. HP items also give you more damage usually or help you deal it. 
could be wrong I guess but armor is more of an afterthought in my opinion until lategame unless you have immediate need because someone is really strong or because you need a particular ability on a particular champ regardless of how good the armor actually is as long as it is cost effective.
