Yes I know what PoS here is used for compared to the "real PoS".
I still didn't know that Steem/EOS/Bitshare use a 2phase protocol that collects two quorums from the majority (2f+1) of witnesses (I will have to read up on this).
In the end that would make it a permissioned blockchain.

HotStuff is like PBFT, it has partial synchrony and is still linear (an adaptation of it will be used in Libra afaik).