Limiting True Damage

Been playing since Season 2, and I remember a point where Morello or one of the Devs made a statement that they didn't want too many sources of true damage in the game because it's so difficult to balance around. Hell, at one point I could name every source of true damage on one hand (Vayne, Darius, Irelia, Ignite), now any champ can get it through keystones or the new IE that's coming out.

Call me crazy, but damage that is only negated by stacking health (which most melee auto-attackers can easily counter with Bloodrazor or Bork) sounds like a great way to push us back to the League of Warmogs era, right after the League of Cleavers when that item was first released. Just my two cents, hoping a red can hop on to provide some clarity to these changes and how true damage will be regulated/why introducing a means to true damage to all champs was a direction they wanted to go.