And with a headset on, they could have still resumed the conversation. Or is it also rude if one tries to sleep? Or if they decided to listen to music or watch

And with a headset on, they could have still resumed the conversation. Or is it also rude if one tries to sleep? Or if they decided to listen to music or watch a movie on the screens? Really the fact is that all those things are normalized and this isn’t. The arguments against it would equally apply to all of the rest of the things people do on planes to occupy their time.