True, but the spamming kind are not known for following best practices.
I think the simplest explanation is that websitetasker is promoting their eponymous website. StudyPool, like Hubski, allows non-authenticated random people to create accounts, then gives them a customizable profile page with a unique URL. This free welcome mat is generous and subject to abuse.
websitetasker has similar profile pages crammed with links at flightaware.com/user/websitetasker, cracked.com/members/websitetasker, flickr.com/people/166815399@N03, and elsewhere.
Some of these sites, perhaps in response to friendly, apologetic requests from other people trying to make the web a nicer place, have removed the spammer's profile since Google's last crawl.
When you see "For a good time call..." scrawled on a bathroom wall, it's possible that the phone number belongs to the vandal. But the best response is probably just to paint over it.