Wayland is developed by the same people who created and still maintain X11. It's been on the works for a decade, but, and it is a big but, it's still experimental. Sure, feature wise it's 90% there, but it also creates a lot of incompatibility issues, as applications have to be made with Wayland in mind. There's Xwayland that is included in most, but not all, deployments of Wayland that run X apps in Wayland, but that has compatibility issues as well. I get a lot of flak for saying this but, Wayland is not yet ready to be the universal replacement for X11, and that is OK, this is not entirely on the Wayland developer's hands. Adoption of new technology takes a lot of time and it requires all developers on board.

Mint precisely because of their “just get it working” philosophy only provides experimental support for Wayland. As X11 is the mature implementation and no software will malfunction for using it, as they are all virtually designed to work with X. However, if you have the latest version of Mint, Virginia, you already have Wayland available to you. Just choose it on your display manager before login in. But it is marked as experimental because some software might glitch.

Mint is trying to create the most straight forward and easiest experience to the vast majority of people. We might have normalized it in the tech circles, but the vast majority of people don't use multi monitor setups. The non-tech people who do, usually do it on an enterprise setting where IT deals with the technical details.