The item support tab is a nice feature. BUT, the fact is a lot of users can’t see it, so I think maybe envato can add a notice section (allow author to customize it) to the top of the comments page, then the author will be able to tell the buyers “read support page first”, “only provide after-sales support for who have really purchased item rather than illegal downloaded our theme” etc.
Or a giant banner pointing them to your Support Forum/Center.
Actually, there is small alert/notice on the “Add a comment” form. This alert will be visible for buyer who has purchased current item.