A true
consensus requires everyone to agree (or, at least, not
object).
You're right.
That is why things like RFA work on "rough
consensus", which
actually just means a vote.
See, my vision of "rough consensus" is something like "If you
eliminate people who !vote without leaving any comment to debate upon,
and who hasn't participate in the debate elsewhere, or who do
something like WP:WHYNOT, WP:NOTNOW, or WP:I[DON'T]LIKEIT what do you
get?" I guess this would be a vote in a sense, albeit a very skewed one.