Yes, I can understand your view.... mostly in forums, what happened is your account is deleted by forum administered if they found that there is no value of your post.
However, forum administers know that it is discussion place and a little marketing stuff may also include but your information should have value.
In forum, your post is not looking natural then there is no advantage of posting any post because it will not receive any click and if it will not receive any click then a major portion of link building effort will be lost as posting only links is not effective link building, it should also receive clicks and how much time passed by visitors on your site counted as determining quality of your website.
So if you think that "I can do" then please tell me what I have to do further.