The problem with hierarchic identifiers is that you need to be extremely dilligent when assigning them, and you make it extremely hard to refactor something in

The problem with hierarchic identifiers is that you need to be extremely dilligent when assigning them, and you make it extremely hard to refactor something in the future. But refactoring is something that happens all the time. For example, you might have "comments" and "posts", and later merge the two entities and call them "notes". Now you have to figure out a way to merge the identifiers -- with UUIDs you don't have issues like this, because they are universally unique. A lot of developers have found that UUIDv7 provides the properties they want (unique identifiers which sort by creation time), and they don't come with the hassle that other approaches come with.