Can you name a single case where this has happened with subscription software, though? The big named examples in the article (as far as I could stand to read it, at least) are Adobe Creative Cloud and Microsoft Office 365.
Here's the What's New page for Photoshop CC 2017, along with links to the changes in various bugfix releases that have occurred since release:
https://helpx.adobe.com/photoshop/using/whats-new.html
You can find the release notes for the past few releases of Photoshop:
https://helpx.adobe.com/photoshop/photoshop-releasenotes.htm...
They aren't sitting on their laurels. And Office hasn't stagnated, either. If the subscription model removes the incentive to do that, why are they still doing that? You get new features in Office 365 sooner than you do on shrinkwrap Office releases. Adobe products have been subscription only for over four years now. The incentive seems to be in place.