No, the objections are stupid. Not only is the Firefox experience vastly superior to any smart TV app, but you can have easy and effective ad blocking on top.
My best guess at why people don't want to do this is that we're conditioned not to do anything that isn't advertised to us, and nobody is running adverts telling you to hook a laptop up to your TV for a superior smart TV experience.
But I also get why people just want to sit on the couch, find a nice video on the phone and with the press of a button want to see it on the TV. No computer boot time, no updates, no writing on the keyboard while laying down.
I get that you can buy a fanless pc, install linux with unattended-upgrades and you have something more powerful. But most people don't know how or don't want to go through that hassle.
Leave the computer running all the time. Never install software updates. Browsing for videos with keyboard is equivalent or better than browsing with phone. If you really want to browse with phone I guess you need a Firefox extension that can send the tab to the laptop. Personally I've never looked into that because I can't imagine wanting to do it.
> Browsing for videos with keyboard is equivalent or better than browsing with phone.
Again, for you yes. But some lay down on the couch and a keyboard in that posture is just annoying.
And copying a youtube video from the app, into firefox app to just send it to the computer is bonkers complicated when you could just press the cast icon.
A lot of people interact with their phone all the time, but rarely use the computer. I'm telling you, it's more easy to use the build in Youtube app for a lot of people.
My best guess at why people don't want to do this is that we're conditioned not to do anything that isn't advertised to us, and nobody is running adverts telling you to hook a laptop up to your TV for a superior smart TV experience.