I'd like to add to this comment about lists vs newsgroups.  Some, like mine,
have developed out of newsgroups.  Even within the "hobby" field and dog
related lists probably fit there, these lists are specialized.
 
There were at least five such lists at Ga Tech alone.  Obviously some will die.
It probably would have happened anyway.  But, they develop because the
newsgroups were not working for them.