Oh I agree; I didn't mean that BBSs were tied to geographical location (though there was some of that), but that they provided a strong sense of online location. You were on a particular BBS at a particular time, not on another one; and you couldn't have 30 tabs open to 30 different BBSs. If it was a multi-line board, you could see who was online at the same time as you. That sort of thing made it feel more like a virtual location.
