Agree with you, the only thing semi useful was whether or not a PC was running in XMP or not. This info can be found very easily in CPU-z.
My own opinion of it is this:
Not only did you get information about the hardware in the PC, RAM and CPU speeds, what drives are present, graphics card, and so on, but quite importantly IMO, background CPU usage. You can ask some unknowing PC user a hundred different ways for them to not understand/comprehend what you are asking FOR because they simply don't know.
The important aspect about UBM is that its results are a composite of every system that has run their benchmark suite. Just like a game engine, some of them are going to be better on AMD or Intel, better on Nvidia or AMD (and I don't think Intel is there yet), but it is telling you that up against every other system tested, your system is "this" percentage of performance against that composite, with this testing method.
The aspect that I cannot understand is why someone would wish to pay to run that benchmark over and over just watching their composite score go down over time. Most users also don't understand that the "decrease" in performance actually isn't their system performing worse, just it falling in the composite rankings against the newer and more capable hardware that are (also) constantly being tested.
As I said before, take with a grain of salt. It had useful features IMO but like many other things that come and go on this ever changing internets of the webz. 😉