for me it's time, it's hard to say for others. There are so many websites out there, they obviously don't know how valuable the information is that they can get here.

Thanks for that Pen, I just wondered why they bother registering and not that the next step of introducing themselves and interact

I've had members register because they thought it would improve their chances of reciprocal links. The rest of the members who register and never post is a mystery to me, but it happens to all websites. I really can't figure out why people register and never post, it makes no sense to me.

I can say that I've personally registered at sites for various reasons and posted once or twice and never again. It was due to many different reasons but mostly because the community was either ignorant or unhelpful in nature.