I'd speculate that there are few who don't participate because they see the site as becoming too commercial. It seems to be heading more that way in the year or so I've been reading.
Truth be known, we have reduced the number of Commercial "industry" entities. We introduced the idea of adding "member's services" - such as "Flipper Rescue" nearly two years ago. We encourage members to add what ever services they can provide to members.
Nino, I don't follow your logic here? Why did you want to reduce the number of commercial industry entities if you want to encourage members to add what ever services they can provide to members. Why some commercial entities and not others? Are you saying some commercial entities are not welcome as members?
By the way I'm not stirring here, but I can't work it out. From the intro and site description that appears on the site welcome page - reading that, to me it seems to suggest the site is far more angled towards non commercial hobbyists, enthusiasts and collectors.
I've really enjoyed and learnt from the contributions of those who do restos and post pictures, details, tips and description even with a few plugs. In this context the plugs have always seemed incidental and fairly innocuous to me.
Maybe I'm too naive, I am purely a hobbyist; I don't seek to make any money out of pinball. I have asked questions and benefited from the site and on occasion contributed where I thought I could offer an opinion or help but truth be told I've always thought a weakness of this site was its' sponsored commercial sales nature - at times it seems to just be a sales advertising forum. It is this angle that I was commenting on as to lowering peoples' desire to participate.