It doesn't really help the author's case that they only examples of extra space after a period they have is with justified text. ALL computer software will add extra space after periods in justified text. In flush-left text, 2 spaces after a sentence just looks bad, period.

I also like how the author manually went in and    after every period just to make a statement.

For the record, these contrarian articles bother me because I'm a creative director and I have to put up with my underlings showing me HN articles saying that design dogmas like "serif text is easier to read in body copy" and "2 spaces after a period is bad" are WRONG and that I'm not listening to the "facts". The problem? They try to prove me wrong and the results look like shit. The author here tried to prove me wrong, but the result is his typography looks like shit. I hope they're happy!