I think Tab Groups is an amazing feature to add.
I really like workspace, but like its name, it's a workspace, and in a space, you would like to group things.
The claim that workspace is operas "tabs group" implementation... well... is sad.
One difference is - I can have many windows, in tab groups, I can have a different tab group for different windows.
but with workspaces I am stuck with the same workspaces on all windows.
Now consider this use case. I have a workspace where I hold all my tv shows, other workspaces for studying, and another for whatever.
wouldn't it be cool if I could group the courses? wouldn't it be cool if I could group the shows?
Sadly if I want to do this with workspaces I would have a very large amount of them, and won't be able to switch with ease even if I use shortcuts....
Point is, workspaces and tab groups are different (in use, in name, in ability). regardless of the intent, seems like there is a real use for it (and many post, requests and such) and I think it would be a good thing to implement it.