Yes, vi can reformat a paragraph without using !child.

[Maarten Litmaath]

tony at oha.UUCP (Tony Olekshy) writes:
\The following macro binding, added to your .exrc, joins the current line with
\the next line, moves to column 78, backs up to the previous word break, and
\splits the line there, leaving the cursor on the next line.  Repeat the
\keystroke until the paragraph is cleaned up. [...]

I'd rather not reformat a long paragraph line by line, thank you.
-- 
"I HATE arbitrary limits, especially when |Maarten Litmaath @ VU Amsterdam:
   they're small."  (Stephen Savitzky)    |maart at cs.vu.nl, mcvax!botter!maart