I believe you misread my comment; I said that the full-screen, minimize, re-size isn't part of the server-side decoration extension, but was part of a more basic xdg_shell protocol through the configure event.

I was objecting to the fact that you said that windows did not have this capability without the server-side extensions, whereas I think they can be through configure. I did not dispute whether sway had server-side decorations or not.