It's not that spam isn't an important problem, nor that it's entirely
out of scope for IETF. But the lack of agreement on the nature of the
problem, along with the level of naivete in these discussions, suggest
that it will be a long time before these discussions can hope to bear
useful fruit. And this isn't a particularly effective venue to work
on that problem.
If nothing else, the NSRG antispam research group has been talking about
this for several months, and there's no point in repeating the same
arguments on the IETF list that they've been having over there.