Does a consensus process need to do that? Not necessarily.
I take as my example a tool on this very page -- RSS.
RSS lets you subscribe to blog feeds like this one, and enjoy may feeds quickly in a newsreader program. There is a consensus that RSS is a good thing, thus most blogs support it. There is a consensus concerning the nature of the XML tags involved.
There is no consensus on the specific RSS scheme to use. Dave Winer's original RSS 0.92 became RSS 1.0 and was followed by a new schema called RSS 2.0, and then a third schema dubbed Atom was created.
There is not even agreement on what the acronym RSS means. Is it Rich Site Summary or Really Simple Syndication?
Newsreaders, and bloggers, support all three. We here at ZDNet use RSS 2.0. All this hubbub is transparent to users.
A good newsreader is designed to handle multiple syndication formats. It can do this because, in an open source world, all the formats are freely available. Were this a dispute among vendors you might need multiple newsreaders.
So even when agreement is not the result of an open source process, the nature of open source allows for contention to continue. Just one of the many ironies in open source.
How many more can you find?