A Hacker News comment, before the autoformatter got to it.

fmtd

Unix fmt double-spaces after periods, except periods after single letters.
Of course, that's only useful to you if you compose text in a text editor,
and pipe it through fmt (or par, if you are that picky), before publishing it.

Thanks to HTML, however, you wouldn't know this text, for example,
had lines about 72 characters,¹ was carefully hand-justified after fmt(1)
to leave no dangling words alone on a line before or after punctuation,²
and had double spaces after all periods inside paragraphs, except T
and S in T. S. Eliot.

 ¹ Except the first paragraph, better broken at “letters”, “editor”,
and “it”, and this footnote, also broken after “editor”.

 ² Though I would rather do that than visit violence upon decent
sentences, like this one, broke at “sentences”.  Obviously it's
preferable to expand and contract margins a bit to suit the text.
Nobody does this any more though, because auto-sizing to columns
destroys manual formatting.³

 ³ Incidentally, these footnotes had to be separate paragraphs,
to keep them from merging with the previous one, and with the
body paragraphs.  What a piece of work is HTML… it delights not me.

Here is this comment before the autoformatter got to it.
https://gist.github.com/catenate/6567903