The popular content on a medium is a reflection of the structure of a medium; not a reflection of the entire population group. The popularity of certain mediums are reflections of portions of population groups.
To have brand new mediums emerge and to compare two mediums as a critique of a population group, unless those two mediums interact with the exact same population group (they never do or else they would be the same exact medium) illustrates a clear lack of understanding as to what functions are at play.
For example, reading a physical book has different pros and cons than reading a pdf and require different levels of knowledge and different levels of investment. Even a slightly different format for reading words targets a different (overlapping but different) population group.
In the past, taking pictures was expensive and in order to even have your picture taken, you had to go out of your way and plan for it and make a time investment. Now, pictures are taken cheaply and easily - and so the medium has changed - thus the population group "photography" targets is different than what was known as photography used to target.
It can be further extrapolated that if the people interested in the fruits of the medium also change, as the product of a medium is its own medium. But this sort of recursion is of limited use.
This applies to anything that is interacted with: change the barrier to entry, change the rewards/penalties, and you change both the average behavior and also change the individual who use/interact with the medium. Thus, to compare across mediums for similar qualities is illogical and incorrect.