There are valid criticisms, for sure. I was not in the original thread, though, so I don't know how willing to address those he is, but it's a valid point that it's not an all or nothing proposition. You can point out that subs aren't overtaking the market in gaming without implying that they should.
I'd be more interesting in debating whether subs are additive or not. I do know of anecdotal mentions of stunted sales on sub-forward releases, but I'd love to see more data about it (and what that means about revenue eventually, too).
But none of that influences the concerns on preservation one way or the other.
Honestly, I don't think you're right about the reasons growth has flatlined. I think the sub model just doesn't fit gaming best. The content just doesn't work well with the rotating carrousel of new and new-ish games most subscriptions have. I think Nintendo could be onto something, in the way Netflix was early on, in that you may be more willing to pay a fee to just have access to every single game before a certain point and from the beginning of time, but nobody is gonna figure that one out anytime soon.
OK, but that's not how reality works, you're making up offenses that nobody has committed because you've decided a particular brand is "bad" while ignoring actual offenses from brands you like and so have decided are "good".
So no, I'm gonna have to say your hypotheticals don't make their offerings any worse (or better) than Microsoft's or Valve's. Now, the pricing and lack of content? Yeah, we can talk about those. But those don't have anything to do with preservation concerns, lack of ownership or content churn, which are all legit issues with all digital distribution and subscriptions.