The shifting canon you describe (“What? You haven’t read the latest…?”) seems associated with a strange form of intellectual myopia. In some cases, groupthink and close-mindedness are involved. Selectively respecting people according to what they have read may have worked when there was this idea that the sum total of all knowledge could be found in l’Encyclopédie. But we now live in a world where “information overload” is a common concept and it’s simply impossible to “read everything.” (Even the whole Wikipedia.)
One strategy to cope with the quantity of written word out there may be to get everyone to read just the very best material (using criteria such as publisher prestige, citation rank, institution name). It’s the approach taken by a lot of PTR committees but it seems counterintuitive in terms of actual academia.
A more appropriate strategy, in my mind, is to make sure we all read different things, and that we allow ourselves to discuss things on those bases. In fact, I tend to think that dialogue is often more important than reading. Call me a linguistic anthropologist.
To a French-speaker like yours truly, it seems especially important to be using diverse sources and the “you haven’t read this???” attitude seems especially problematic. If I were snarky enough, I’d be able to retort with pointed remarks about how inappropriate people’s use of French authors has been, over the years. “So, you think you understood Bourdieu? Well, I have news for you…”
But I snark rarely.
If I remember correctly, Parker Palmer’s The Courage to Teach (it might have been another teaching book) had something about making a list of the journals to which colleagues in a department are subscribed so that a new hire could subscribe to journals which aren’t in that list. The concept being that we shouldn’t all cover the same ground. Seemed like a very good idea, to me. It could prevent a number of turf wars and academic fads might have less impact.
We haven’t even talked about interdisciplinary or non-disciplinary work.

The second point is about the legs on which the tenure system’s hegemony stands. Although there is, in fact, a reward and punishment system in place, the tenure system depends not on coercion but on a sort of agreement about The way things “work.”
With all due respect to those colleagues, even some of those tenured and tenure-track academics who wish to be the most “radical” in discussing the tenure system seem to agree with the fundamental ideas on which that system was originally built (and which serve for its maintenance). Simply put, some people who are highly-trained critical thinkers seem to have some difficulty thinking critically about the system in which they live. “Oh, sure, there are problems with that system. But, at least, we have this system to protect us.” To a relative outsider, this seems especially strange. Protect who? From whom?
The broad situation with the tenure system is in a (boiling frog slow) process of getting closer to “banally evil” bureaucracy. In hegemonic, not totalitarian context. Many people complain. But many of those still seem to believe that they depend on the tenure system to survive.

Ah, well…