One of the features of maillists is that posts of the sort, "I agree,"
are boring and rather pointless. Also, regardless of how careful or
slovenly the given poster may be, it is usually too time-consuming to
rehearse all the points of agreement prior to expressing a [different,
contrary, contradictory, polemical] viewpoint.
This is one of the reasons that threads are apt to be reduced to
artillery fire from entrenched positions at one or two elements of the
initial post in the thread.
Also, it occurs to me, an "offensive" position expressed by a faceless
party who only exists on one's screen is apt to engender a more
emotional response than the same position expressed over the table in
the coffee shop would have.
It's really rather surprising that all members of an e-mail list do not
hate each other.