The hard part of the problem is that by creating 'spaces' full of tabs to make our lives easier we create yet another categorization, another taxonomy, and with it all the timeless problems that taxonomies have: Should the current page belong to category A or a similar category B? Or to both? How can I merge two spaces into one in a good way? Can I do it automatically or do I have to, yet again, select, curate, categorize? How can browsing and researching be a living process and at the same time be neatly sorted for later recall?
One thing that I kind of still miss after watching the field develop for four years, is the simple idea of making groups of tabs easily shareable. Just let me share a tab group with another person! Better yet let us work on the same tab group together, treating it like a living document, a living research space.
I guess this can't be solved by an alternative browser, but instead by an open standard that could be implemented in all browsers.
[0] https://rybakov.com/blog/open_tabs_are_cognitive_spaces/