Where did they get "proprietary" from? Proprietary is relating to an owner or ownership and the Steem blockchain is not (to my knowledge) owned by anyone.

Sorry sir, but you are utterly wrong. At a level of content and tokens you may be right - even though the steemit was sold with its tokens and licences, the rest of tokens belong to users. One need to look at the whole ecosystem. When you rip off a significant part of economy/ecosystem - steemit is a major window for user of greater value than tokens themselves - you either take users as hostages go with me to decrease your losses or die with your crippled economy.

Major player f*** us over and forced us into China-based and prone to censorship hands.