This doesn't really fit as the discpline of Engineering was generally licensed and regulated where, in many countries, you could only call yourself an Engineer

This doesn't really fit as the discpline of Engineering was generally licensed and regulated where, in many countries, you could only call yourself an Engineer if you adheered to certain standards and got the respective diploma/license. Gatekeeping (in the pejorative sense) is about not clearly defined groups that members want to make exclusive against certain people/groups, e.g. being a fan of something ("you are only a true fan if you can name the last five albums in chronological order") When you compare the rigour (esp. in testing) of nomrla engineering disciplines and software engineering, you should be able to spot a difference