I would argue that DRM free downloads are much closer to truly owning your games, since your "ownership" isn't tied to a media that will wear out or decay, and which likely cannot be backed up

In theory perhaps. In practice you can get physical media on second hand markets long after it is out of print but for digital media the publisher effectively controls availability (which also means they can keep the price high). There is effectively no right of first sale in practice for digital media which IMO makes it clearly not ownership.

In practice physical media also has a longer lifespan than the average persons handling of digital media. And wheter you are allowed to make backups of your physical media very much depends on your country.