Part of the advertised benefit is that it is indeed blocked by walls and such, allowing very fine-grained segmentation of access. The idea is that you’ll just have more “access points” wherever you want coverage, so, every room etc. But within one room, I believe reflections will allow some propagation, so that things like briefly blocking the direct line of sight won’t actually drop the signal. Also it’s all in infrared, so not visible to us at all.

Now, to be clear, I am sceptical, as an electronics engineer I can see many challenges here. But I can also see that there are solutions to those problems; it will just take time. The advantages, where relevant, are really big.