Yes, I agree with the author and believe that this is what he is saying. Multiple reasons though. Initially it may have just been greater returns in the roi enticing SBD demand. Now its likely just increased circulation extending out the SBD lifecycle thereby reducing circulation supply (its not just hitting the mkt upon receipt). Additionally, new class of passive income delegators are unlikely selling their SBD daily returns the second they get them, which leads to increased attrition in SBD supply circulation (active bidders to less active and more passive investors and then delay before selling). I also believe were now reaching a point of excessive supply due to this large run up in the steem price which results in more and more SBD being issued. I think thats what the author was getting at.