Meta-question : why so few "Re: " subjects ?

Dear Colleagues -- As a newcomer to the group, I am finding
it very difficult to find my way through the plethora of
messages as so few have a "Re: " prefix in the subject
line even when they are clearly replies to earlier
messages.  Is this an intentional part of this list's
protocol, or is it an artifact of the widespread use
by list members of an e-mail client that does not
automatically insert this prefix ?

Philip Taylor