In my head they're akin methods, and so in software that idea of "call this from lots of different places, edit it in a centralized way" concept is pretty well established.
In terms of "a single document flowing with a single voice" you can't necessarily do that from assembling an arbitrary collection of blocks like that, but for "good enough for effective in-corp collaboriation"? Sure!
I think that (and the problem of bait-and-switch) still need an answer before it's usable beyond small groups. Maybe small groups is good enough for now. If it goes in any form like software development, we'll at some point split into two camps. One will say YOLO and just implement shared blocks, trusting in good will, and the other group will noodle on foundational principles to get this right. (Group 1 will make the money, group 2 will have the fun. As always ;)
And yes, it's closer to Engelbert's vision. We've been getting closer to that (and the Memex) for a long time, and we'll continue to do so. They are distant visions what a future could look like, while we barely understand knowledge work. I mean, the term itself is already an improvement of clarity on the ideas of the memex.
If you compare knowledge work to Mathematics, I'd guess we're shortly before Elements. We're at best about to understand the basic building blocks. Which I find tremendously exciting - we're still at the very beginning of exploration.