I don't really get this criticism. How are "overall sales" over a period of a century or two relevant to anyone in a business context or assessing the health of the industry?
There are plenty of unencumbered digital formats distributed physically that are unrestrictable. Red Book CDs/CD-ROMs, DVDs/DVD-ROMs, and to a certain extend Blu-ray/BD-ROMs (and lesser extent, but still possible UHD Blu-ray). At conventions indie devs sell digital copies of their games on flash drives.
There’s nothing wrong with digital media (defined literally). While I like physical copies, even file based digital media is mostly OK. The problem is DRM’d media regardless of how it’s distributed.
Reverted back to physical books and I don't think I will ever buy e-books again. I just love having them piling up on bookshelves, love when people come visit me and can see some of my interests by peeking into the shelves, and love when someone asks me to borrow one of them.