Yes, this creates a difference between narrow and broad money. I have considered this possibility.. What I was pointing out is that this system is a bit obvious. Increasing steemit safety by slowing its cashing out time is something that can do any crypto. Bitcoin too, for example, would have a new rule (via hard fork) that forces users to wait some time before of being able to spend received sum. By this point of view steemit is not a tecnologic evolution. It is simply a different balance of this tradeoff using blockchain.
Obviously, we also have to consider the other aspects such as steem volatility and similar problems for using steemit as money. I agree with what you said in your reply, i am simply saying that we have to consider the difference between STEEM narrow money and SBD broad money.
By the other hand, steem Power is more similar to an investment in my opinion. 3 month to cash out is really too much, and SP creates the possibility to get new cash flow.. Just like a financial security.