Tl;dr: Let old products go 404, or redirect to home page? A client of mine has recently made the switch from one CMS to another. They run an e-commerce business, but also have physical locations. About 70% of all their products were expired, and so these URLs had no meaning to them and thus were not transferred when migrating.

When doing the redirects mapping, I figured I would prioritize all the URLs that had traffic, backlinks, and otherwise were important. Due to the redirect tool we use, I did not have time to go through every URL from their old site.

Now, someone is telling me that I should have opted for actually implementing redirects for the remainder of the URLs, even sending them to home page rather than just letting them go 404.

I did my research back then, and I did even more when this came up: Nothing points to there being any benefits to redirecting to home page when there is no relevant content otherwise.

I could redirect to a category page, but I did not have time for this, as I focused on more relevant redirects. So instead I let about 14k URLs go 404. Mind you, these had (almost) no traffic and nothing "worthy" about them that would make them prioritized. Many of these products were expired for many years, but they never cleaned up their site.