One of the things people may not realize about many online communities is that there are usually far more members who simply read than post. Or post only very occasionally. There is a lot to be gained from other people's wisdom, opinions and insights, without having to contribute one's own (or feeling like you have nothing to contribute).

So I would never require a member to post, nor delete their account simply because they haven't. It's just not important to some people (yet they still want a sense of "belonging," hence the reason why they register)...

DocJohn