Apple has been doing low latency screen mirroring for, I don’t know, a decade. If you find the latency unacceptable, consider looking into your network performance.
For a quick tech demo, it's all fun and games, but when there is real shit to do, nobody wants to fight their tools.
I can see why it is completely fine for your application but you can't say the same for other applications.
Besides it doesn't even make much sense to need that when the thing has such a powerful processor, Apple need to get their shit together and have it run real Mac software and that's it.