I would also recommend people look into notmuch.
More promising is this fork of mutt that adds notmuch support:
notmuch doesn't replace mutt, you use it with mutt/offlineimap etc as your mail indexer, which makes massive mail archives instantly searchable.. (and does this extremely well)
I suspect this what the grandparent was referring to, it's not intended as a mutt replacement, so to complain that it doesn't replace it well is a bit unfair
(notmuch is mentioned in the original link, btw)