What are valid reasons not to use hard links?

Choosing not to use hard links is valid because they are specific to one filesystem. Hard links create a direct link to the data of a file on the filesystem where they are created, meaning they cannot cross filesystem boundaries. This limitation makes hard links less flexible in scenarios where files may need to be shared or referenced across different filesystems, which could be necessary in various applications or system structures.

By contrast, soft links (or symbolic links) can span filesystems, allowing for greater versatility when dealing with file locations across different storage devices. This characteristic can be crucial in certain setups, such as when managing files in a complex directory structure involving multiple mounted filesystems or network locations.