There is an issue in that Grady does need to end his long lines (== 
paragraph) with
a space, or fold them with trailing spaces; otherwise his lines render
as "fixed" in
the format=flowed regime, which causes them to _not_ be folded for
display.

The other side of the coin is that that spec _recommends_ folding at <78
in the
composition phase in order than a user whose mail reader doesn't
understand
format=flowed can still see somewhat well laid out text.

To take an example, I'm writing this message in format=flowed but 
folding my lines
at <78 (with trailing spaces to indicate reflowable text). The display
_should_ be
nicely flowed to match the reader's reflow settings. But if you pipe the
raw message
data through less you should at least see text folded before 78 chars,
which
accomodates simple message inspection or incompetent mail reader
software.