(BFtreee) ... enable a more decentralized proof-of-stake protocol by eliminating the need for two classes of nodes and delegation to a small number of validators. We view the goal of scaling to millions of validators as a forcing function to create a more scalable consensus
algorithm where BFT is no longer the bottleneck in terms of
making cryptocurrencies more decentralized. In practice, other bottlenecks, such as block sizes, may make the ideal number of validators be tens or hundreds of thousands of nodes for large cryptocurrencies.