www.html-faq.com/etiquette/?toppost
Why should I not top-post?
The internet is all about communication. Communication is the eliciting of a
response. Effective communication is the eliciting of a desired response.
Trolling is the stubborn assertion of a view that the poster knows to be
obnoxious to the community of readers.
This newsgroup thrives on threaded discussions. There's no way to build a
threaded discussion with top-posting on a newsgroup whose majority members
conventionally use bottom-posting with selective relevant quotebacks.
Top-posting severely inhibits others from understanding the conversation,
because the context of the conversation is lost.