Something you need to keep in mind is that web content is a two-way street. I always list my sites in my sig. Heck, I was making a sig at HR before they allowed automatic sigs in every post.
On average, you'll find that folks who have some sort of professional affiliation in their sigs are also going to make more solid, experienced and knowledgeable contributions. Take everyone out of this forum who has a business-oriented link in their sig, and you take away a huge % of the quality posts. Take those away and you lose readership.
When I make posts at HR I provide content for HR. Better content makes for more readers. More readers means HR can raise advertising rates. HR makes money from the content of the people posting here.
If need be, you could say I pay my way at HR for having my sites linked in my sig by providing content for HR.
I'm also not anonymous here, and don't waste bandwidth by posting a bunch of psycho shit.