The way SEO works is as follows. You want the google page rank algorithm to put your page very high. One way to do that is to have other websites link to it. This works best, if the other websites are legitimate, important and popular so SE would be a good target. So you post a reasonable looking question on SE that contains a link to your website.
I suspect that this question and this one where created with this purpose (I have no proof, they just look that way to me).
Question: Should SE try to fight being used that way and if so, how?
The first linked question is marked as duplicate, but that doesn't change anything here because it still appears in regular searches. The questions would need to be closed to thwart their use as SEO.