Only in part jest.

Some people really use their cellphone as a crutch for all sorts of things.
A few co-workers were busy on their cellphone one-quarter of the time at a annual Christmas restaurant lunch.

None of them have jobs which require that they be on call.
I thought it was rude. Thankfully yaaked happily with 2 other colleagues (1 in her late 20's, other closer to my age, who didn't pull out their cellphones at all.).