well definitely don't buy that. You don't need to vote for 21 of the nodes, votes are ultimately set by network stake anyway. So votes don't count 1:1 per person, and witnesses are elected by total vested voting weight.
Especially as EOS plans to be a much bigger network than steem, for all types of applications to be built on top of, it seems like this number of witnesses is an unnecessary restriction on the network.
RE: EOS: Explanation of New BFT+DPoS w/ Daniel Larimer - Part 2 of 2