You are mistaken. You are not on the list.
Apologies if the intended humour wasn't obvious.
I don't know for certain, but I suspect that the forum administrators and moderators don't want to have the responsibility of trying to decide which signatures are valid, and which are part of a campaign.
Removing sigs entirely would obviate this responsibility, no?
perhaps the site administration feels that high quality posters should be allowed to benefit financially through advertising for their participation.
Most people perceive and expect a clear distinction between advertisement and content, and ad sigs blur this significantly. If advertisers want to advertise on the site, they should do it through traditional channels, that don't introduce obvious conflicts of interest.