I think it's more the detail they lost (or do not agree with) is that working successfully in multiple environments can valide the strength of the design. Some people will look at a slightly different structure underneath and see it as noise and hassle instead, where you or I may see their action as taking unnecessary or questionable dependencies.
The short version is that the Linux ecosystem has for whatever reason spent a decade or so resolving the already-solved problem of "who is logged in to this TTY?" and came up with a new way to solve that that the BSDs don't in general implement and Wayland relies on.
