Earlier quoted context omitted.
Meh. Whenever I see such things, it's usually because their interlocutor is boring. People aren't interesting just because they are people. In fact, most people are boring as hell. There is such a thing as manners, of course. But that's a two-way street. The other party also has to make an effort to not be boring, and that effort is rarely made either.
>>> The other party also has to make an effort not to be boring, and that effort is rarely made either. Would you please elaborate what you mean by this? I am familiar with how conversations work or at least how they used to... This looking at your phone and tuning out of a conversation seems to be somethin new and lacking as you said, manners.
I find demanding someone's attention more rude than not giving attention that's requested. Someone's attention is theirs to give, not something for others to demand.
As for how conversations used to work... When people were boring or uninteresting people would zone out and just uh-hu away. Just smile and nod. It may give the other the illusion that they're not being ignored, but they are.