Yep, you don't seem to know what you wrote.
Why would I faff around resizing windows, when I can pin an app to the side and it takes 1/4 of a second to do.
I do this often when I have a spreadsheet or website where I'm entering data and need a calc. Calc is full function btw and guess what I can have as many windows as I want on desktop same as I always have, so how is this a step back?
What exactly have I lost? Oh wait I haven't lost squat and gained yet another tool, a tool that saves time and effort and works extremely well.
Same with twitter when I'm watching f1, no fafing about and works properly, as its designed for the space, not all desktop apps work well at all sizes.
Step backs means we've lost something, so what is it? Nothing, nothing at all.