Fair point. I'm guessing I'm one of the people you're referring to?

Lets be honest though, majordomo style lists are a bit archaic these days. 

I know I've replied to the list before and my reply has ended up appearing as a top level thread, although I've still no idea why.

I'm sure Im not alone in wondering exactly what the bare minimum is I need to quote, in order for it to appear threaded.  If you're happy to guide us through that, Im sure I wouldn't be the only one to benefit from it.