If you buy on Etsy to resell you would not want anyone knowing where you got your top secret stock from, so you would protect your sales AND YOUR FAVORITES.
Favorites are not only a way to show love, but a convenient way of bookmarking items for purchase later.
So if you spend $10 in findings and 3 hours on making a necklace you sell for $40 you would not want your customers to get wind of your top secret stash shop or they would just go and buy the items and make the necklace themselves rather
than your OOAK original.
So I think people who do a lot of reselling may protect their favorites. So anything they favorite comes up as a secret admirer.
Something to chew on..