It doesn't matter for me if a game client is installed locally or not. The difference is that the game is controlled by the server and you cannot run it without contact to the server. Although some marketing folks try to sell us the bright new future with a thin client and everything else running server side I already would count all the present MMO and browser games to this category.

To be honest games as a service doesn't need to mean that. Yes, that is what most people do mean when they use the phrase, but games as a service taken literally would mean treating a game as an ongoing project rather than a one off thing that is completed and shipped and forgotten about (beyond a few patches and DLC).
The problem with this is that it is not profitable to the developers unless they can make money out of it in the long run (new sales can only account for so much revenue after initial release periods, particularly if you are aiming to be successful and be something most of your target audience wishes to buy straight away), and this usually means subscriptions or microtransactions.

So while it may not be particularly feasible or profitable for DRM free games as services it's not mutually exclusive.

DRM-free Gwent would be competing with regular DRMed Gwent, and as soon as someone writes a hub and alternate deckbuilding rules (I know at least three people capable of the feat who are also very good at CCCGs) you can stick a fork in the game. So, not gonna happen.

I have 6 Gwent decks from the collectors editions of the Witcher DLCs.

More formally Games as a Service is just a constraint of (general) Software as a Service (SaaS) model, which is the new trend in software industry, applied to video games.

In short the whole idea is that the user owns nothing, everything is cloud based and a subscription is required to access the service.

Of course the whole practice imposes DRM.

https://en.wikipedia.org/wiki/Software_as_a_service

As expected references from the industry state many benefits!
https://www.ibm.com/blogs/cloud-computing/2014/03/what-is-software-as-a-service-saas/
https://azure.microsoft.com/en-in/overview/what-is-saas/

How many games that are not DRM free based on your definition of DRM-free (since this as we saw in this discussion is not as objective as people think) are here at the moment and why? O.K. - we have GWENT because of microtransactions (which are not requuired to play the game) and mandatory being online with an account. Any more?

If you're serious about this, you're asking in the wrong place. Gog isn't developing Gwent, CDP Red is.