The recent implementation of a -5 karma penalty for replying to comments that are at -3 or below has clearly met with some disagreement and controversy. See http://lesswrong.com/r/discussion/lw/eb9/meta_karma_for_last_30_days/7aon . However, at the same time, it seems that Eliezer's observation that trolling and related problems have over time gotten worse here may be correct. It may be that this an inevitable consequence of growth, but it may be that it can be handled or reduced with some solution or set of solutions. I'm starting this discussion thread for people to propose possible solutions. To minimize anchoring bias and related problems, I'm not going to include my ideas in this header but in a comment below. People should think about the problem before reading proposed solutions (again to minimize anchoring issues).
I mostly agree with you that the statement against technical solutions is false on the face of it.
How about this: if you want to prevent certain types of discussion and interaction in an online community, the members need to have some kind of consensus against it (the "social" part of the solution). Otherwise technical measures will either be worked around (if plenty of communication can still happen) or the community will be damaged (if communication is blocked enough to achieve the stated aim).
Technical measures can change the required amount of consensus needed from complete unanimity to something more achievable.
In our case, we may not have had the required amount of consensus against feeding trolls, or of what counts as a troll to avoid feeding.