> there's a very good reason why the long-
> established way to participate in a mailing list is quote the salient
> bits of the prior email and directly reply to individual sentences or
> paragraphs right underneath them. So that readers know what answers go
> with which questions.
>
> It's called interspersed replies.
A lot of the big providers have made doing this far more difficult than it used to be. I have personal experience with Gmail, where I used to be able to highlight part of the message, and that was all that would be included in my reply, but that no longer works; the entire message is included and I have to manually trim it. Gmail also top posts by default, which may also account for the increased amount of top-posting we see, particularly if other large providers are working the same way. In short, it takes a lot more work than it used to take to do interspersed replies, but it is still possible if you climb the learning curve and put in a little effort.
--Greg