...I've found a blog I'll be keeping/catching up with...

Thanks :)

Web browsers are used for multiple activities...

Something I've concluded Web browser developers put insufficient thought into. They're also far too often optimizing for content providers and advertisers rather than readers.

...a whole set of tabs ... related to a general activity...

Quite. And I'll often have multiple projects going on, each with their own set of related references.

The failure of the Desktop (and GUI) paradigms in general to reflect this is a growing and tremendous frustration of mine. Our activities are organized and grouped by application and increasingly by Web silo rather than by task. It's where the UNIX shell philosophy is increadibly powerful, and the abilty to both create different "workspaces" (generally: directories) for projects, and to string data through commands and pipelines, is phenomenally useful.

Just to highlight a frustration: increasingly desktop tools are utilizing Web tools for documentation. I arrange my work by Workspace. So when I fire off the Help command in a particular utility ... a browser tab opens somewhere three workspaces away, that I'm not aware of. Often in the midst of a bunch of other unrelated tabs....

For example...

Excellent use cases, and while my own work differs in details, the general outline is the same: different tasks, often persisting across days, weeks, months, or even years, but alternating with time, which I wish to group. Often quite complex and involving many related sites and/or pages. And retaining that user state is at an extreme premium.

Bookmarks don't cut it for me in this regard....

I'm leaning toward a middle ground between Bookmarks, History, and some level of annotation. Readability is an interesting experiment but ultimately frustrating and limiting.

My own curated lists of stuff are somewhat useful but extremely tedious to create. My subreddit is as much a bookmarking tool (of both Websites / references, and my own thoughts) as it is a publication and discussion.

The ability to create and readily access sets of bookmarks, tag and tab them, filter them usefully (by tag, author, site, dates, etc.) would be tremendously useful.

I'd really love a browser feature which let me search for text within pages I'd recently visited (hour, day, week, month, ...). Often what I'm looking for is something I've already recently visited.

It is* possible to organize Bookmarks hierarchically, etc. But I find that the UI/UX for doing this in numerous browsers is simply tedious beyond description.

...some combination of tab pinning, tab groups and tree style tabs, and tab suspension/delayed loading...

Yes to all of this.

For Pinning, I'd prefer to simply break out Web Apps as their own local app instance. Not associated with a browser at all. While Web-as-App-delivery is interesting, it's ultimately highly frustrating in my experience. A neither-man-nor-beast experience.

Tab groups...

I'll need to play with that.

Tree Style Tabs...

I use and love the plugin (for Firefox), and use it much as you do Tab Groups from what I can tell.

...tab stacking...

Not familiar with that.

...delayed loading of tabs...

Genius.

1. Memory management/unloading of old tabs

2. Tab group classification or tagging

4. Open the browser to the tab overview page

A-fucking-men to all of this. Your point that there is no overview page for tabs, or similarly that there is not way to perform group operations on tabs, is another massive failing.