OK, it's true that there are compromises with a folding bike … but what kind of bike is there not a compromise with? I'd like to point out that everybody doesn't use the same tool the same way. For me, the folding bike is great because it's compact and I can carry it in my car or my truck or the back of an Uber/Lyft easily. I'll never fold it, probably.
But also … when I was looking for a lower bar to accommodate my lack of hip flexibility, the Bike Friday's low crossbar was what was really attractive. There just aren't a lot of other bikes with crossbars low enough for me to step over. (My other bike is a Trek Verve with the low step-over, but other than that form factor, there's nothing.)
I'm just saying that the compromises that people think they're going to suffer--inferior pedal-rotation to ground covered--is just not the case.