When considering the stat efficiency of defensive items with offensive perks, particularly late game slot hogs like Atma, there is something people (and Riot) often fail to factor in.
Last Whisper and Weapon Expertise.
Sure, I'll pay 700g for 378g worth of armor. I'll buy a chain vest and make it into an item that eats up a slot to get a cloth armor worth of defense.
Atma's is not a defensive item any more than Madred's Bloodrazor or Wriggle is. It gives Crit and AD. The 24 effective armor late game does not make it a defensive item.
Wriggles is also somewhat of an issue of tanky dps, particularly in the laning phase.
The players bring this upon themselves when they use the same builds OVER and OVER again. They want offense AND defense without having to compromise. What you get is the nerf bat.