Basically, on any sane window manager no matter if Wayland or X11, you'll get the same frame for all apps for free. From all the big desktops it's only GNOME that somehow decided server-side decorations weren't a good idea implement, and now all Wayland apps have to hand-roll a hacky workaround. The "flat frameless window" look was Electron's GNOME workaround. What the article is describing is a more elaborate GNOME workaround. On e.g. KDE, none of these problems existed in the first place.