[StockHuman]

Tab groups work better with OS functions than multiple windows past a certain number, which is generally dependent on the physical size of one’s screen(s).

Exposé on MacOS can get very, very cluttered with more than ten windows open from various apps, and distinguishing between them can be rather cumbersome if the content between the last opened tab of any given window isn’t visually distinct from another. The same is true in Window’s implementation and in their taskbar preview feature. The same is also true with tiling window managers, as every new window becomes something else to manage, where perhaps a “browser” slot should really occupy just one consistent tile.

Full-screen workflows (common on small laptops) also benefit from a singular “browser” screen, flanked by other applications instead of numerous windows whose minimization needs to be managed.

That, and managing tabs between windows is annoying, especially with rules to open a particular link within a given window, since that might break a setup as above. (Imagine a HN link summoning an entire separate window, reconfiguring your desktop setup, when the errant click could’ve just switched tab groups.