Why is 144p even a thing?

Watching on a phone screen doesn't require as much detail since the video is shrunk down to the screen, having the lower number of pixels reduced the data load while still allowing for good apparent quality on something small like a phone.

So I suspect that it is because it reduces the cost to phone users via their data plans, and because it's not necessary to have more pixels anyways in that use case.

Music videos and really shit wifi.

I have a 2mbit internet connection, when I download anything I'm glad that option exists so I can listen to a video.