There certainly are use cases. Such as when at work using 3 apps mostly, with a dual-screen setup, it wouldn't make sense to give each app one third of the total screen area, as one app would be split onto two screens.
As for differences between such ultrawide screens, this one can e.g. daisy chain further screens, it can charge laptop directly from the docking station (accessible from the front), it can run input from two PCs side-by-side, and with the KVM-switch also letting one work on other PCs with the same keyboard and mouse. From what I know, not every such screen comes with such features. And sometimes it can be just about availability. E.g. when U.S. will soon be producing screens of the 23rd century, but not allow export of them to anyone, there still is a demand for screens elsewhere.