So I heard thornmail can effectively counter lifesteal now. Hmmm
When couldn't it? The damage return is calculated before armor even takes effect.
-Attack is initiated (200 AD)
-30% in magic damage is returned to attacker (60 MD is returned)
-return damage is reduced by magic resist (assume 30 MR base)
-return damage to attacker (46 MD)
-damage is reduced by armor (150 armor, 10% entry, 85 AD)
-damage is subtracted from target (85 PD is reduced from target)
-lifesteal kicks in (25% of 85 = 21)
With just one bloodthrister (before nerf, assuming 100 base AD and 50 base armor on enemy), you're only healing 21 damage out of the 46 you took in this case.
Assuming your target is just standing there taking it with no other enemy units around:
Attacker takes 25 damage.
Target takes 85 damage.
So yes, you could still kill him this way, but you cannot fill your health, especially if he's fighting back.
You also have to consider this, thornmail costs 2000 gold, where the bloodthrister costs 3000 and needs to fill itself up.
So yeah, thornmail was already good at countering lifesteal.
Thornmail isn't involved at all for why they nerfed the lifesteal items. It's a legitimate concern when jumping into the jungle for 2 seconds heals you more than Soraka throwing Wish, Heal, and Astral Blessing on you.
