I think this question always poses something about status insecurity as the old discussion of what makes a "true" software developer.
Engineering and Software Development share a key characteristic which is about inventing and implementing things.
The key difference is that engineering is fundamentally based on applied physics and math where software development doesn't care about physics because it's an already solved abstraction in this discipline.
I think you're right about the underlying concern about status. My sense is that people in this discussion are really asking whether software engineering is just easier than mechanical or chemical or aerospace--or whatever--engineering. That's also why I don't think calls for certification standards really address this concern (you can just as well be certified to do something easy).
the absurdity of the question becomes clearer if you start thinking about the right tool for the job. if you need to invent facebook you don't start with reinventing the wheel but with applying software development. it's the right abstraction for the job. and no sane mind would claim that serving content to billion users a day is an easy task but in the end it's just software.
