You can disagree all you want, but a thread on a forum is for discussion. You can do what the post says, but you can also discuss it. If you don't want to start a discussion, post elsewhere or send people emails.

Just a few definitions of forum (emphasis mine):

a public meeting or assembly for open discussion
wordnet.princeton.edu/perl/webwn

An online discussion group, where participants with common interests can exchange open messages.
bugclub.org/glossary.html

An online discussion group or newsgroup (see USENET).
www.saol.com/glossary.asp