It depends on the use case, I guess. Miracast is good for quick sharing of content stored locally on your phone/laptop, whereas Chromecast is better suited to stream content that is hosted elsewhere, so it doesn't drain your battery.

That’s a single use case and you can just reverse it and have a ‘remote control’ mode on the portable device.

In practice people are now buying Telescreens (not like there’s option tbh) and they have Android or at least Netflix already built in.