We've actually dug a bit deeper. We're working with a data scientist right now who has been analyzing data throughout the marketplace to better understand what impacts a product's potential to sell.
We'll have a blog post on the findings later this week but the quick answer-
After digging into the data, turns out backorders do very little to impact a product's potential to sell. After turning on backorders, a product sells very, very little - almost none. It seems that customers don't like backorders - or at least don't do it nearly as much as when the product is in stock.
Because of that difference, it may be that backorders hurt a product's longterm success. Displaying the 'Join the waitlist' button is the alternative. With the waitlist, customers buy in mass - and very quickly- once a product comes back in stock. My guess is fear the product will sell out again.
It's a question of keeping backorders (and the few orders that come in while a product is soldout) vs default waitlist and the flurry of activity that comes once a product is back in stock. Hard to compare those against each other - but we know for a fact that backorders do very little across the marketplace.
