Why would anyone still choose X11 or XLibre instead of Wayland?

A major reason is that some desktop environments are still transitioning. GNOME and KDE have strong Wayland support, but environments such as Xfce, Cinnamon, and MATE have been slower to provide mature Wayland sessions. People may simply prefer those desktops and wait until their Wayland implementations are stable.

Some people also stay with X11 simply because their current setup works and they do not want to spend time replacing tools or adjusting their workflow. Others have older hardware or distributions without a polished Wayland session. The transition is well underway, but there is no single deadline when every application and desktop will work equally well on Wayland.

XLibre is a separate and controversial continuation of the X server, not a reason that most users need to avoid Wayland. Critics argue that it has introduced regressions and instability, while supporters see value in maintaining an actively patched X server. In practice, users who need X11 compatibility can usually use the established X server; choosing XLibre is more of a project and maintenance preference than a general requirement.

X11 is old, widely tested, and has decades of compatibility behind it. That does not make it the best long-term choice—Wayland generally provides a more modern security model and handles some features better—but X11 can still be the practical option when a particular application, driver, input setup, or workflow depends on it. XWayland helps with many older applications, though it is not a universal replacement for a complete X11 session.

X11 is still useful when your desktop environment, window manager, hardware, or favorite applications do not have complete Wayland support. Some older or highly customized window managers are X11-only, and certain systems still behave more reliably with it. Wayland support is improving quickly, but compatibility depends on the entire desktop stack rather than just the compositor.