> generally everyone would use the Netflix app on the Apple TV (which is solid) rather than airplay from their device

Only people that have Apple TVs. Apple has sold a lot of them, but it's a fairly niche device that costs 3x what this one does. They also work differently so that you're not streaming from your device to the Chromecast dongle, but that you're essentially just telling it what to play (you can then use your device as normal). This is pretty neat, I for one would use it just so I would not have to deal with the terrible Apple TV remote control anymore. Typing in anything is a frustrating experience, I'd rather type from my phone or computer and then have it play where I'd like (my TV).