Right, and as I said elsewhere, this is a problem with the reference implementation being crusty, not X11. That seems to be the point the speaker is making as well.
Like, I'm fully supportive of having the X server simply manage DRI3 for a bunch of clients and composite the results. That's all well and good.
I'm less supportive of doing this while also removing all support for the other things that the X server provides the ecosystem:
* Unified input/event capturing and forwarding
* Unified screen capturing/recording
* Window management
* Clipboard
* Structured IPC (on top of which you get ICCCM and NetWM)
* Xrdb
* Xprops
* Notions of windows in general (everything's now client-side)
* Fonts
* Drawing APIs
These were all standardized things that users could count on always being available, regardless of which GUI programs they used. Wayland completely punts on these things and defers them to extensions.
Before you ask, I've already seen the "Wayland is a protocol; these are all extensions" song and dance routine. That's a cop-out. Dropping these things means that there will now be multiple incompatible implementations of the same concept, and no way to mix-and-match them because they now all have to be built into the same process that does your window management. Wayland implementations completely destroy this digital commons, for no apparent reason or gain for the users. The only people I see potentially benefiting from this are full-fledged DEs who can leverage their compositors' incompatible implementations to enact a form of lock-in (i.e. your GNOME programs are no longer guaranteed to run in KDE, and vice versa). So, why do this?