From the Orchid FAQ
Why Orchid chooses to remain an E-mail based Community?
The big advantage of mailing lists over a web based message boards is
that the content gets to you rather than you having to go to the web
to get it.
We do realize there are many good 'community' sites out there that
rely on nothing but web based systems, and that works well for them.
However, Orchid's current format is in our humble opinion easier to
follow and 'digest' if one chooses, while providing more
accountability and 'get to know your neighbor' type interactions.