Agreed, the fact that SOG becomes necessary for a variety of decks to be viable means that a variety of decks aren't using more interesting and niche forms of resource acceleration. This actually gets at the problem of just how much interesting practical design space is blotted out by one OP card that becomes the crutch.
Since SoG is more powerful than the "more interesting and niche forms of resource acceleration", why do you think that decks that need SoG to be "viable" would still be viable if they used the "more interesting and niche forms of resource acceleration"? And is there really a benefit to driving decks that are on the edge of viability out of existence?
Since "more interesting and niche forms of resource acceleration" already exist, exactly what "practical design space" is being blotted out by Steward of Gondor? I can understand the sentiment that the *many* resource generating player cards in leadership would be more popular if Steward of Gondor didn't exist -- Dori has a similar complaint against Beregond. But the many niche and interesting resource generators and deck accelerators are proof positive that an attractive general-purpose *need not* close that space off against additional cards. It's encouraging to see the designers have recently provided so many alternatives to A Hasty Stroke. I hope A Test of Will alternatives are in the pipeline.