Resistances are basically worthless

So, playing mostly tanky champs, I have to say...there is no god damn point in building any resistances at all when someone builds up either or cause it basically makes ALL resistances null. Playing as one game, I built up a good amount of health, armor and magic resist...and yet I was getting uber shit on by a , getting hit for fucking 2k auto attacks...2k. That is absolutely retarded. So, you either have to stack pure health, which a good amount of champs can hit you for True Damage, or build up purely one resistance, and still get shit on cause they have 35% piercing. So, if they could ACTUALLY make resistances be viable, that'll be great...