Such scores are clearly possible. If you define a one-dimensional scale you can project everything onto it. Clearly you lose a lot of information in doing so, but if your scale is "overall utility" of some kind and that utility is the only thing you care about, then of course you can do it.
In principle anyway - you can't actually calculate someone's utility. It's a thought experiment.
But the one-dimensional scale also brings in a lot if implicit assumptions that you have to be aware of - e.g. that you can add or subtract individual utility values and the result will still be meaningful.
In principle anyway - you can't actually calculate someone's utility. It's a thought experiment.