The evolution of filtering (a story from the Usenet era)
When I first started reading Usenet (back in the rather old days), I
wound up hanging around some old Unix and Usenet hands. One of the
things that I noticed about how they read Usenet was that they had
really aggressive killfiles; they would go into what I considered a
high quality technical newsgroup like
comp.unix.wizards and their
newsreader would promptly junk all but one or two of the articles.
At the time, I did not understand this at all. Sure, there was a certain amount of pointless chaff even back then, but they had to also be throwing out huge amounts of solid, interesting stuff; how could they stand to miss them?
I took the opposite attitude. For a long time I didn't use a killfile at all, because I didn't want to run the risk of accidentally missing a good article. Even when I started using killfiles, I was very conservative about what I junked; I felt it was better to wade through some amount of chaff rather than miss a gem.
Then one day I woke up and realized that I was wrong, because I had been fooling myself about the actual choices. In reality it was not a choice between reading only some of the gems or reading all of the gems (and some amount of chaff); it was a choice between effectively reading no gems at all and reading at least some, even if I missed others. Once I realized this, my Usenet filtering gradually became more and more aggressive. As the noise increased in the newsgroups I read, I became more and more willing to filter out almost everything in order to at least get something or at least not waste lots of time for nothing.
There is an obvious extension of this to email, and in fact I've wound up feeling that the same dynamic is inevitable. Put one way, there is only so much noise that people will put with for so long. At some point I expect people to switch attitudes the way I did way back when, and stop feeling that every email is (potentially) precious in favour of an attitude of extracting what use they can from email, even if it's imperfect and incomplete.
(Existing spam filtering is already helping with this, because it means that fewer and fewer people consider email a reliable communication method any more. 'It got eaten by my spam filter' is a great excuse partly because it's so often true.)