The New Bounty System is to Blame as Well
The Frostmancy strategy has found it's way into league partially because of the bounty system changes that occurred a few patches back. One part of those changes in particular has caused Frostmancy to exist. That mechanic that was added to the bounty system is the farming bounty. The farming bounty is given to an individual that has been farming better than the average farming of the enemy team, so if your top laner doesn't farm than the other team will start acquiring bounties. The whole bounty change has had mixed feeling with the community, but because if these horrendous strategies evolving from the change I think it would be totally logical to remove the changes.
Riot should remove the farming bounty and make bounties start at 3 kills again