Those who gather here have widely different education, experience and
interests. Yet there is (almost always) quite sufficient common overlap in
the discussions to give the list a critical mass. Those for whom that is not
true tend to leave in search of a list/group that more closely matches their
requirement.
There is one other point I think. The quality of argument in this list is,
more often than not, of a high quality and well informed. It's higher than,
in my experience, is commonly found elsewhere, especially where politics, in
one guise or another, is central to so many threads. It may be that others
who stay with this meandering list also appreciate this.