To be perfectly blunt, if you think an item where you sink half the cost into defensive stats and tools doesn't count as a "defensive item" in a game where the best offensive items get you gold efficiency of 95% to 105% from raw offensive value, then your itemization is kinda trash for DPS.
I mean, another hybrid offense-defense item in Maw only gets 62% efficiency from offensive stats, and while that's booted up to 83.6% while its passive is active ... that is actually a lot of value missing from the passive, because most of it is dedicated to defensive effects. Not to mention that offensive value from the passive is worsened by the fact that you need to take magic damage and be taken below 30% health to trigger it, meaning that it has to be carried with other defensive stats to leverage it well or else you'll just get blown up by physical damage before you can benefit from it.
Also, to put it in perspective, Bloodthirster is 78.9% efficient from raw damage, but it also has a huge chunk of life steal that is always active, which means that its main defensive component scales really well with DPS, unlike GA's armor and revival which don't interact with DPS at all, or Maw while inactive and doing it far worse while inactive. It also effectively provides 120 - 350 bonus health depending on how soon you get it, which is only a bit under the health Sterak's gives late in the game, which makes it a completely efficient item ... at level 2, when that effective health is 60.
Blade of the Ruined King is another example. Its minimum offensive efficiency is only 71.8% in comparison to Bloodthrister ... if it's attacking a target with less than 188 health. Against a target with 1000 or more health? 118.4% of offensive stats and rising at the health rises, before factoring in defensive stats. Which, since it gives only 5% less life steal than Bloodthrister, also scales really well the user's DPS, which BotR provides a lot of bang for its price tag against anyone who isn't limping or severely underleveled. And that's before factoring in its active, which is a great tool for offensive chasing or defensive kiting ...
I mean, BotRK is even really good right now.
It's really just you guys having arbitrary definitions of what's "right" for a DPS's defensive item. As long as it's life steal or otherwise has no offensive value whatsoever, it's fine. As soon as armor or magic resist find itself on an item with 20 AD, though? Comment chains like this happen. It's pretty inane, especially from the perspective of someone who plays both League and DOTA.