Yes it does. If nothing else, the archives are used to
provide canonical URLs for referring to messages.
What might not be clear is the need to run a search
engine on the sourceware server, especially if it
puts an awful load on the server at times and especially
when "foo bar site:gcc.gnu.org" on Google works just
fine. However, I have come across (rare) instances where
Google does not show any results for such a query
even though I can manually dig out such a message and
the message was posted quite some time back.
Google is heavily pruning gcc.gnu.org mailing list archives. gmane does
not, but then you have to go back to the archive and find the canonical URL.
Note that if you access GCC mailing lists via gmail (which I do) you
have a permanent link in the headers, something like
http://permalink.gmane.org/gmane.comp.gcc.devel/74787 for Ranjit's
message. Maybe it could be possible to add a similar header (caveat
emptor: I don't know anything about mailing list management software)?
Paolo
