[Karunamon]

Humans aren't single-threaded, most can glance at their phones mid-conversation with no interruption.

Your second paragraph amounts to a kafkatrap (wherein denying the validity of the argument automatically means it applies to the denier).

[Barrin92]

Humans actually are kind of single-threaded, excessive multitasking has a measurable impact on mental performance. It's trivial to observe for yourself. Try to read and book and interrupt reading every few minutes. You will notice that you will both have to spend more time (by definition), and retain less information. Not to mention that interrupting actual conversations to stare at your phone seems kind of rude, asocial and inconsiderate.

>(wherein denying the validity of the argument automatically means it applies to the denier).

this isn't really a great point when it comes to addiction, because it's a genuine behaviour among addicts, not just a way to attack one personally. Addicts will downplay or deny the role their addiction plays in their lives categorically.

[Karunamon]

Unless you have a lot more knowledge about someone than can be gleaned from one or two comments on HN, you lack the context to determine whether someone's use of a thing amounts to addiction.