No, you need to watch out for the -1x programmers. At least the 0.1x are moving forward,

I agree, because the effort required to filter out a 0.1x programmer is vastly smaller than trying to find a 10x outlier. Way more bang for the buck.

This is just rescaling. The author is actually acknowledging that there exists 10x differences but divides by 10 for some reason.

The author's point is that more effort should be spent removing negative outliers instead of hunting for elusive positive outliers.

1x is supposed to be a baseline for an average productive programmer.

0.1 is someone who isn't actually a productive engineer but somehow faked the interview process.

It's not difficult to be 10 times more productive than somebody who isn't productive at all. I'm at least 100x better Kotlin developer than my 30 years dead grand-grand father who never saw computer IRL.

It's much more difficult to show that you can be 10 times more productive than the average productive developer.