Rather begruddingly I have begun to wonder the same.
I had, by quite some margin, my biggest off last year, which resulted in a broken elbow, fractured nose, lost tooth and split from nose to lip. Like you I was able to freewheel back down to the car & drive myself straight to A&E.
Also like you, I was on my own but late in the day @ CwmCarn and on a section I’ve ridden loads of times before with no issue. I still don’t actually know how I crashed, but due to the bent R/H crank arm I think I caught a root/rock which threw me off. My gloves were spotless despite the rest of my being drenched in blood and mud, so I didn’t even have time to put my hands out to break the fall.
I’ve been out since, but very cautious and now I’m not too keen (nor my fiance tbh) on riding alone, which is a shame as it means I’m riding less than I used to 🙁
Healing vibes to the OP too. Should be recovered just in time for spring 🙂