It's been said once in the comments, but the emphasis on "strong vs single tank comps" couldn'T be expressed enough. Teams with bruisers that want to cheat their build and go damage (like a hydra/lw/cleaver j4) that leave their amumu/naut/sej/hec/ etc. alone to tank will collapse in team fights after you just destroy their initiation.
I always type both in champ select and before team fights to "FOCUS MY ULT TARGET" which i ping 3 times to make sure lol. You'll still get lee sin's flying in the back because they think its cool but at least your adc can shred their tank in 5 seconds. So good vs singed!