Not everything is for you.

But to answer your question, it’s nice to keep things grouped up by window, especially with a tiling DE, but to still be able to split/tile that workspace within the window and have the system treat it as one entity.

One project or subject per window. I use an extension called Winger in Firefox which essentially allows me to manage windows as tab groups; but it is also sometimes nice to use some kind of tab grouping (and now some split views) on top of that to help organize things within the context of that window.

I used to just be a “one windows with 600 open tabs, GLHF” kinda guy, but that is just a miserable way to live. Like i said, maybe all this stuff isn’t for everyone but when you need it, it’s nice to have - and for some things I appreciate a native implementation that we can extend with extensions instead of relying on every extension author to get right from the ground up.

Say you're redoing an image in photopea, you can have a split tab woth that image and photopea, so the image you're replicating is only there while you're trying to recreate it, and not any other tab.