> better than nothing, [which is sometimes the only other option]
True. The trick is to sort of mentally keep track of how much better than nothing it is, so you know which pieces of anecdotal evidence you can trust with only 40% confidence, and which you can trust with something more like 90%.
But yeah, definitely WAY better than nothing.
As you say, though, LYAH is almost certainly not at 99% market share. It's definitely not at the 100% market share HTML has in Web development.
The universe is too complex to design a statistically-valid study for everything you want to know (though I definitely understand the urge to do that). At the end of the day, anecdotal evidence may not be great, but it's often better than nothing, and nothing is often the only other practical option.