Tendermint works great for 4 to 300 validators, and with the Cosmos delegation model, many more stakers can participate. So yes, it's not a trivial problem, but Tendermint is solving it.
I don't know of anyone who really applied traditional BFT networks into public blockchain architecture, however, until Tendermint.
For example, who spoke or wrote of BFT fault accountability/attribution, and how it pertains to proof-of-stake models, before Tendermint?
There was also the 2011 paper that lamented the lack of good open-source middleware for BFT algos. Tendermint solves that engineering problem as well.