Consider environments where the need to monitor time is invariable, yet smartphones are prohibited on grounds of security, safety or for some other reason. It’s an industry norm to prohibit smartphones in warehouses, a common place of employment throughout industrialized-nations. I’m sure you could think of others if pressed.

From your comment I think you’re referring to wrist-watches. My understanding of the wrist-watches’ popularity is that it was a remnant of the war economy. The military needed personnel to keep track of time; pilots in particular needed wrist-watches for navigation. After the war those factories that mass produced for national militaries still existed and found a bludgeoning middle-class market to sell their gluts: the fashion wrist-watch. The population were conditioned to wear them during war and that behaviour carried on after. I think a similar thing happened with belts too.

It’s rather amusing to consider that pocket-watches have now made a comeback, only they’ve changed form and now offer other functions. Nearly everyone has a pocket-watch; it’s rectangular rather than circular in shape now. Certainly bigger than they used to be. ;)