SBD is now $7 and STEEM is 50 cents, barely higher than Hive. Steem has gone out of their way to break SBD again, and it hasn't helped the price of STEEM the way you suggest.
You are confusing cause and effect. Both STEEM and SBD went up a lot in 2017-2018 because there was a tremendous spike in speculation and demand throughout the crypto market. It wasn't a matter of SBD going up being the cause and STEEM going up being the effect, they simply both went up.
I have to tell you what actually happened when sbd and steem went up 2017/2018.
There were 2 + major catalysts.
There was tether fud, lots of dollars went out of tether looking to find another “peg”. At the time, not many existed, which flooded Steem Backed Dollars with intense buying pressure.
there were lots of funds exiting bitconnect and entering steem. 2 big moves were made by Trayvon and Craig. They both market sold their bitconnect and market bought steem pushing the prices way up high.
Bonus fact) also, voting bots were a thing, they accepted steem dollars and steem, thus creating a major use case for both tokens (buying pressure).
I have not suggested in any fashion that the high SBD price has helped the price of steem. Reality is, the content creators are getting half steem half sbd, just like us, but their peg is $7 while ours is being pushed down.
Now if this behaviour can actually propel hive’s price then why not, go for it. But right now lots of 3rd world steemit users are praising the high SBD price, if only they knew their funds are controlled by a master manipulator.