To establish the authors of an article, it would be most sensible to
do a word-by-word blame (annotate, whatever you like: who last
modified each word -- or better, each token, given that wikisyntax can
theoretically be tokenized) and just use that as a list. If someone
contributed in the distant past and their contribution was later
totally replaced, that's nice of them and all, but they aren't really
a contributor to the present version in any real sense.