> I am aware that the kernel configuration files specify which drivers
> are compiled into the kernel.  Yet is there any Webpage, Website,
> mailing list, or Wiki which chronicles the decision(s) for including
> those drivers found in the default kernels?

These decisions are usually discussed on the port-foo mailing lists.
Basically the rationale is to be inclusive if it won't hurt
(e.g. GENERIC on i386, tuned for largish memory machines), and sparse on
INSTALL, trying to make a kernel that is maximally useful, which is a
delicate balance between large size and enough drivers.  The commit logs
for the kernel files are probably also useful in understanding the
decisions.

All that said, sometimes drivers are in or out because they used to be
in or out.