I'd say the data is pretty meaningless - at least the stuff presented in the picture and article - as it doesn't compare X11 and Wayland running the same desktop environment. It's X11 Xfce or Wayland KDE or Wayland Gnome etc. So who is to say whether it's actually X11 or Wayland contributing to the differences? Comparing Xfce - a low power desktop by design - with Gnome or KDE is not a fair comparison; Gnome and KDE have way more bells and whistles. It's interesting that X11 xfce4 under stress uses more power than Wayland KDE under stress, but it may be meaningless.

I'd rather see the figures of X11 xfce4 and Wayland xfce4 but the Wayland version is experimental at present so unlikely to be fair. X11 KDE and Wayland KDE would be a better comparison, but even then it reflects how KDE has developed their Wayland version, not necessarily just how Wayland compares to X11.

In terms of power usage, if that's the primary concern, then go for the lightest weight desktop and run the least amount of software possible (including services). Switching from X11 to Wayland is not about power consumption, and a 1 Watt difference on a desktop PC that could run anywhere from 100 to 700 Watts isn't meaningful. Even on a 100W low powered device, I'd question how important a 1W difference is.