Is Ignorance the Only Reason for Internet Forums?

I don’t understand why Internet Forums need to exist — the only “feature” I can make out not included in most blogging software today is the ability to ignore another user (seems sort-of anti-social to me, but whatever).

Does anyone need forum software to exist?

Indeed, I don’t even see a need for wiki software to exist — the “Page” feature includes most of the features that are “crucial” to managing information in groups.

I guess it ought to be clear that I think WordPress has become the web’s “Swiss Army Knife” — I really don’t need anything else (and even if I did: there’s a very high probabability that “there’s a Plugin for that” ).