I don't understand the problem.  You only have to read the new part.
Since most mail clients used on this list put the new part at the top, it
very easy to skip the part you don't want.

On Tue, 24 Nov 1998, Richard Sims wrote:

> >This is a "working style" difference for those who use digest
> >and those who don't.  If you don't use digest, it's far more convenient to
> >see the entire included message and all the predecessors directly below the
> >new entry.  This is particularly true for those of us who may be absent for
> >the list for a week at a time and then come back in the middle of a
> >conversation.
>
> This issue was extensively discussed some months ago, and we heard from the
> List administrator what a burden it was for the list server system, internet
> bandwidth, and mail recipients to have the whole thread of a topic
> cumulatively repeated in each new response to the topic.  It's excessive and
> is more of a negative than a positive.  Having huge mail items arrive in one's
> mailbox is counterproductive all around, regardless of whether you use the
> Digest function.  It's like being spammed rather than getting concise info.
> It's wasting people's valuable time to have to wade through volume like that.
> It's ridiculous and without need.
>
> The Subject line of the mail item should be used to uniquely identify the
> topic, making it easy for programmatically compiling and humanly following a
> thread.  To respond to a point, you simply need to reference that point or
> include just that extract - not the entirety of the thread.  This approach
> makes everything run faster.
>
> If you are off the list for some time, remember the List archives, which are
> marvelous for scrolling through and searching - which, again, the unique
> Subject lines help navigate.
>
> The whole efficiency of ADSM is in its incremental approach.  Let's adhere to
> that same approach as we employ ADSM-L mailings.
>
>      Richard Sims, BU
>