Intentionally useless or meaningless

Solution 1:

There's a term for the joke. From Wikipedia:

In its original sense, a shaggy dog story or yarn is an extremely long-winded anecdote characterized by extensive narration of typically irrelevant incidents and terminated by an anticlimax or a pointless punchline.

Solution 2:

Trammeling on someone's expectations

This prank goes back before iPhones. My grandfather, an old-world carpenter, used to build do-nothing gizmos:

There are a number of different variations, but they all share the "do nothing" characteristic:

_{source: Kuntz Carpentry catalog of wooden puzzles}

Of course, the true purpose of the device was to amuse himself, when he'd hand the device to his wife (my grandma) with no explanation, just to enjoy the baffled look on her face as she'd crank it one way, then the other, to no meaningful effect (the shuttle, or whatever the piece that slides in the channels is called, simply moves back and forth or up and down as you turn he handle; it never "does" anything).

Now, it turns out these devices originally did have a practical purpose, before they were converted into prank toys.

They were called the "Trammel of Archimedes", and were used to draw ellipses:

That Wikipedia article¹ notes:

Wooden versions of the trammel of Archimedes have been produced also as toys or novelty items, and sold under the name of Kentucky do-nothings, nothing grinders or do nothing machines. In these toys the drafting instrument is replaced by a crank handle, and the position of the sliding shuttles is usually fixed.

Elliptical answer

Going further, the Wikipedia article also notes there's a broader category of device which includes these novelty items, named Useless Machines.

The canonical example they give is "the box that closes itself", which can be seen in action in this YouTube video:

A more sophisticated example is the electro-mechanical Do Nothing Machine on display at the Museum of Craftsmanship, in Carlsbad, CA, demonstrated in this YouTube video.

The docent in the video relates an anecdote that the inventor had a guest over who saw the device, and on studying the machine for a while, quipped:

You know, there's a lot going on here, with no results, you ought to have called it "Congress"

¹ _{Which also includes animated gifs of the device in action, which I can't embed here due to technical limitations.}