Spammers are becoming more numerous, more determined, and more bold in their assertions that their promotional additions somehow constitute legitimate content.
Editors rarely look beyond the last one or two edits before drawing conclusions and thus tend to believe the most outrageous claims, despite persistent, long-running patterns of abuse as long as they're buried deep enough in the spammer's edit history (i.e., more than the most recent edit or maybe (and only maybe), the one before that).
Van Loon is in fact a long-time anonymous editor: The first edit that I can identify is a spamlink of his consulting company, http://www.lc-stars.com, into ISO 15504in August of 2005:
"One mistake he made was to add links to a product that he created."
Van Loon is a consultant who runs the Switzerland-based LC Consulting. What User:Sbowers3 calls his "mistake" is really a three-year effort to promote his consulting business, as follows:
Anonymously spamlinking his consulting company's website into various articles (note: this is only a subset and extends back as far as 2005 and 2006):
"I submit that Hanvanloon has made useful contributions, that his few edits that might have been COI were not efforts to promote his product, but were simply good faith attempts to improve the articles by adding what he thought was relevant information."
The fact that he actively vandalizes legitimate content, to which he has admitted, should be proof enough that he is up to no good:
His persistent claims that publication in the American Society for Quality's (ASQ) Quality Progress somehow makes his efforts to inject his books for sale and "methodology" into Wikipedia non-commercial: