I can see how that would help if your filenames are bin, dev, opt, usr, and var, but in the general case, I do not see how that beats having a longer hash (or a second, independent hash).

Four bytes of the name will have less entropy than such data, and having part of the filename around will not help making sure that a matching hash implies a matching filename.

Can you give explain this or give a name of a filesystem doing this?