I'm more surprised at the fact that they didn't appear to have tested it on themselves first.
FWIW, at least Microsoft still "dogfoods" (and it's what coined that term), and even if the results of that aren't great, I'm sure they would've caught something of this severity... but then again, maybe not[1].
This is what really would concern me too. With this wide spread issue any reasonable testing should have detected it. Having a few dozen machines with different configurations for an few hours should have detected this. This should have been in a smoke test.
Push update to machines, observe, power cycle them, observe...
I could understand error in some rarer setup, but this was so common that it should have been obvious error.
FWIW, at least Microsoft still "dogfoods" (and it's what coined that term), and even if the results of that aren't great, I'm sure they would've caught something of this severity... but then again, maybe not[1].
[1] https://news.ycombinator.com/item?id=18189139