Daryl,
As others have stated, you can't explain it.
Bill,
I also hosted Michael and Jed along with many others.
When I play with GCA'ers and others, I'm always asked how I know them, and like you, when I reply, "through the Internet", I also get that dubious look.
First, I think that golfers are a unique breed that bond quickly and that GCA'ers are a unique subset of golfers who also bond quickly.
Common interests tend to do that.
The architectural "get togethers" that I've hosted have accelerated the bonding process as they allow names on an Internet site to meet, share their common interest, and play golf together.
And, when you meet another golf course architecture buff, the common interest almost immediately bonds you.