Then what was the point of the rest of the comment?

I was giving my opinion on what I consider a great design choice of Emacs by not having such windows by default.

I suggest you to reconsider if you really want a popup frame (posframe). One of the great features of Emacs in my opinion is that it does not by default create popup frames for user input like other programs. I suspect because of its origins as a terminal application. Don't you ever get frustrated by applications that have such popups which quite often appear on a different workspace! I'm not suggesting the posframe solutions others have suggested also suffer from this behaviour.