I lean towards the idea that for a lot, they are outraged by the fact that THEY, being the special snowflakes they are, were deleted - of all the unmitigated gall of an admin to exclude them! They had so much to say, so much wisdom to share with the plebians! It is now a point of honor and selfless duty to the others on the forums to heedlessly eschew forum moderation to bring their Message to the poor captive forumites. They then also usually cry freedom of speech, no free will, or other things that show they don't understand that websites are private and personal expression is a privilege and not a right.