Well of course it does, what else would it represent?
We know that the total number of registrations includes people who have registered more than once (presumably they have their reasons), but we also know that they represent only a tiny proportion of the overall total. It's also true that there are lots of people who register and only visit us now and then - but they aren't the majority. We know exactly how many times each person has logged in, so we know what our average audience is. About a year ago we were ABC rated at 1.3 million page impressions a month. We had far fewer members then, and the current traffic levels are higher.
To be honest, I'm not quite sure why anyone feels the need to post like Salinger did - what's the problem with what Pesala said? We know that thousands of people visit us each day, and we know that many of them get real help from real people - surely that's what counts isn't it? The fact that the registration figures continue to climb - albeit more slowly now - is an indication that we're providing a useful (free) service, which is something that a lot of computer magazines can't be bothered to do.
It doesn't seem that long ago that we used to have a regular little unofficial competition every Friday or saturday night, to try and guess how soon we would get to say, 10,000 or 15,000 members. I think that zero to 125,000 in just over three years isn't bad going. During that period lots of other forums have opened up, had a go, and called it a day, while we've been steadily growing in size.