It is also annoying to deal with people who never remove quotes they are not replying to. Bottom posting encourages the removal of quotes beyond a certain level; people who top post routinely ignore the quoted text.
I guess the point of the article is not that bottom posting should die, but that quoting messages at all should die. Remove quoted text or make it optional, and the bottom/top posting argument goes away entirely. If you assume everyone receives all messages anyway, what is the point of quoting?
(Edit: Personally, I would rather not give up quoting, because messages may be lost and I would like to see whatever context I missed. It is also nice to see the context of a reply; "That is a bad idea!" could refer to anything in a message, bottom posting helps to clear it up.)