Some computers don't have many USB ports - the one in the article photo only has two.
I agree that it's not very useful. There's probably a complicated way to achieve something similar using a proper hub, a bunch of sticks, and software. But most people are fine with a bunch of sticks for different things - "my live boot OS", "my music", "my photos", "all my other stuff".
More useful would be a USB stick that came with stickers to describe content - cute little camera icons or music stuff. Or at least a strip that the user can write on (with a pen, not file system) on the case.
As others have said - it is pretty though.
A long time ago (when they weren't dirt cheap) USB sticks came with labels. For some reason the new ones don't. Probably because I don't know anyone that has more than one big USB stick. Why would you need 4 USB sticks? They are slow enough to make them unusable for large data.
If I want to plug multiple drives in, I just do. There is no reason I need to plug them into each other.
Whoever made it probably imagined that the drives would share a filesystem (i.e. one drive letter for all of them) - but did not think it through since doing that is too complicated to be practical.