... snip ...
But a mistaken newsgroup redirection will rapidly get corrected in
that other newsgroup. The problem isn't so much the extra answers,
it is those mistaken answers. The answerer may be convinced s/he
is completely accurate, and wrong.
A wrong answer will also get corrected in the other newsgroup. I
don't disagree with the redirection part, I disagree that there
should only be redirection and no other reply.
Also, the answerer can be one
of the ugly trolls we have been plagued with recently, who post
much misinformation.
The trolls aren't going to heed your request anyway so they are
beside the point.
Adhering to topicality takes advantage of the separation of
newsgroups in Usenet. Ignoring it discards that advantage, to no
net purpose.
I'm not advocating ignoring it; where we disagree is the precise
manner in which one should adhere to it.