Why doesn't forward-paragraph save-match-data?

[Alan Mackenzie]

Emacs 21.1.

I came across this while trying to sort out some obscure code.

forward-paragraph, which gets used within elisp code as well as being
bound to M-}, modifies the match data.  Neither forward-paragraph's
doc-string nor its info-page mentions this.

Given that there is no intrinsic reason why forward-paragraph has to use
a regular expression search, this seems to be a non-intuitive thing to
do.

Is there any good reason for this behaviour, and if so, what?

-- 
Alan Mackenzie (Munich, Germany)
Email: aacm@muuc.dee; to decode, wherever there is a repeated letter
(like "aa"), remove half of them (leaving, say, "a").