As someone who both produces and buys on Envato, I can say I’ve had trouble with this on both sides. Whenever I buy an item, I always forget to leave a review even though I’ve seen authors complain about a lack of reviews which makes me feel bad about it. Months and months later, I might remember to do it while glossing through my downloads to redownload something, but only might.
On the other hand, when someone buys an item, I want to know what they think of it, I want to know if it got the job done and if I should make more items like it.
Even though it’s easy to leave a review, remembering to leave one is not on my list of priorities when I’m in the middle of a business venture, there is just no incentive for it. What I can say is that when I do leave reviews for items I buy, it is usually after I have had a personal conversation with the author, like emailing them to ask them how it works, if they have different versions, refunding or etc.