Let me rephrase this for you. A lot of so-called "knowledge work" is just tedious, mind-numbing bullshit. Not only that, but you have to plow through it while fighting information overflow and your own overly complex tools, while acting completely alone. There are no librarians on the Internet.
No wonder everyone craves distractions.
>In the context of the browser, how do we contextualize pages and interactions inside some abstract task?
This train has sailed off its tracks long time ago.
Browsers aren't real tools. They are designed to make for smooth information consumption so that Google and co can harvest your money and attention as efficiently as possible.
I can list several hundred things a web browser should do if it aims at being "knowledge worker's tool". Let me just give some categories:
1. Features for pausing and restarting work in different mental contexts. 2. Local personalization. Shit like Timelines should be local and user-controller. "This is too complicated, so let's let Facebook/Twitter/Microsoft do it" is a lame excuse. 3. Did you notice that browsers still don't have any good authoring tools? Every websites reinvents their own WYSIWYG. "Developer tools" have everything for debugging, but almost nothing for creations of stuff. 4. User-driven integration between pages. (For example, something as simple as "when I open this page, go to that other page, find all the entries with word X and paste it here".)
Bah, that's enough. I can continue, but I think the point was made, unless the reader doesn't want to see it on purpose.