The other day, I was shopping online for a gift for my sister's birthday. Eventually, I saw a stylish black leather wallet that I thought she would love, but I was rushing and decided to buy it later. On the next day, I returned to the same website, but the wallet was gone. "That's a bummer! It must be out of stock"—I thought.
To check if there was another option to buy that wallet, I contacted customer service. However, I didn't know the SKU code, couldn't recall the model, and the only thing I could do was ask the online sales assistant for a"gorgeous black leather wallet". Unfortunately, they sell many of them, so she could not understand the one I was referring to, apologizing for the inconvenience.
The practice of unpublishing out-of-stock products is very common. This is actually the standard behavior for many ecommerce sites. However, I do not understand the value of this choice. When a product runs out of stock, displaying its page on the website opens up many business opportunities that would otherwise be lost if the page was removed.
In the case of an omnichannel retailer, for instance, you can swap the add to cart button with a find in store call to action. You can also implement a "remind me when back in stock" feature. At the very least, you can still keep a reference to the product on the page, so that a customer looking for that product can communicate with the brand more easily.
In my shopping experience described before, if the product page had still been available, I could have communicated the SKU code to the sales assistant instead of struggling to describe the product details, and I'm sure that she would have been able to help me better.
The SEO impact of unpublishing a product page is also significant. The best way to retain the link juice from a product page after it is removed is to 301 redirect the URL to another relevant URL, such as the category page. While this approach may be better than responding with a 404, the target page is only relatively relevant, as it is not showing that product anymore but a list of products that are somehow related. Additionally, managing 301 redirects based on stock availability requires additional effort that can be avoided. It is much simpler (and more valuable for the customer) to keep an out of stock product page published. It's a win-win situation that should become the norm.
In the end, visibility and sellability are very different concepts that must be treated differently. The problem is that most traditional ecommerce platforms provide this behavior by default, which explains why they aren't. Product objects and product pages are tightly coupled on those platforms. In fact, the product object exists only to store information about the product page content. This information includes the title, description, image, attributes (which is content) as well as price and availability of the product (which is commerce). Availability determines whether the product page itself will be visible or hidden. The product page is published if the product is available, otherwise it is unpublished.
To me, visibility of a product is a merchandising concept that should be separated from its sellability. If you usually think in these terms, try taking a step back. Rethink what products and variants are. Separate content from commerce. Keep your product pages live even when out of stock. You will greatly improve your customer experience, SEO, and ultimately your business overall.