I wonder how many people remember why they changed GA.
Back in the day, in season 2, thornmail and GA were considered bad items for tanks to pick up, since they discouraged enemies from dumping damage into you, and as a tank you wanted to bait the enemy team into dumping as much damage as possible into you. If you died mid-teamfight, your team probably won that fight, since the enemy team had wasted a bunch of damage on your tanky ass.
But then damage grew higher, and tank stats weaker. Again, and again, and again. And tanks started picking up GA, 'cause otherwise they'd be focused and deleted at the start of teamfights, because why not? They're slow, low damage threats. Sitting ducks. Damage was so high that it didn't matter if you used your shit to burst down the tank, you had plenty left. And so tanks needed to discourage enemies from just blowing them up, otherwise their slow, unwieldy kits wouldn't have time to do anything.
And people started complaining. Because killing a tank with a GA was a huge pain in the ass. These stupid goddamn tanks were super hard to kill, and that was a problem.
And Riot listened and decreed that no longer would GA be a good pickup on tanks. Not because tanks were being given independent tankiness, but because GA would now build out of a FUCKING BF SWORD.