- It's expensive and cost-inefficient.
- You'd only buy it on a tank.
- The passive sucks.
- It only works well against carries, but the damage return it deals is pretty negligible as the carry can easily mitigate it with lifesteal.
- People have to be focusing you for it to even be the least bit useful, and if no one doesn't, you just wasted money. And no one with a brain will focus on the tank.
- You could buy an item like Frozen Heart for almost the same amount of armor and more and a better passive that benefits your team.
The only scenario I'd imagine myself buying it is when the enemy team consists of 5 AD and I often find myself being focused. But, personally, if I'm the center of attention, I'd rather buy a Randuin's.