Engineering used as a title should be regulated in the software industry; it was always a title reserved for a role that requires accountability. In software, it became used so casually without legal restriction that full stack developers started using it.

This is most often pushed on the person by their company. I don't have an Eng degree nor certification, but my company forces my title to be "... Engineer", which I dislike, but I've been told this is just how it is.