Comment by rkangel

Wayland is a significant improvement in one specific area (and it's not this one).

All programs in X were trusted and had access to the same drawing space. This meant that one program could see what another one was drawing. Effectively this meant that any compromised program could see your whole screen if you were using X.

Wayland has a different architecture where programs only have access to the resources to draw their own stuff, and then a separate compositor joins all the results together.

Wayland does nothing about the REST of the application permission model - ability to access files, send network requests etc. For that you need more sandboxing e.g. Flatpak, Containers, VMs