I wasn't the person that made the claim - but since I feel the same way (well, maybe not quite as strongly!)... I find I often lose track of earlier messages in a thread that I haven't yet responded to, because I reply to some other message from someone else who replied later. I also find that other people make the same mistake and as a result fail to reply to my emails to them sometimes.
I find emails much easier to deal with when the actual emails are in the list, rather than the conversations - although when displaying the message there's no reason not to show it in the context of the conversation.
He/she is clearly trolling. Saying that a popular feature is "the single worst software feature ever developed for any piece of software ever made" is meant to illicit strong emotions, not conversation.
I find conversation view confusing because a) it often compresses individual emails which then get lost b) it conflates emails which clearly do not belong to the same conversation. The former regularly causes colleagues to miss important email. The latter is common with automated mail.
I always turn it off, but I think conversation view might be worth it with the following changes:
1. When viewing a conversation, always expand all email and cut quoted text from each email. The fact that quoted text is shown which duplicates email in the same conversation makes for a horrible mess.
2. Use the proper headers (Message-ID, IIRC) to determine which emails belong to the same conversation, rather than the current fuzzy-logic based on the subject and current phase of the moon. At the very least, implement this logic: two separate emails, neither of which are a reply to another email, do NOT belong to the same conversation.
