To me, the use of "stepping stone" job can be confusing inasmuch as it tends to connote being on a particular path, where each stone on the path is related to the next.
Entry-level jobs, or "gateway" jobs are not intended to be "stepping stones" in that sense to better paying jobs or careers (unless of course someone's chosen career-path IS at Wendy's or wherever).
What they really are, imo, are "make do" or "get by" jobs while the person is doing whatever else they may be doing for their career (e.g. going to school, apprenticeship or etc.). They are low (if anything) career expectation positions intended strictly to earn some income while taking steps towards a career elsewhere.
I've been a stock boy, paper boy, delivery boy, a sacker, a checker, a prep cook, a steak chef, a bartender, a janitor... none of which are career positions or "stepping stones" to a career. They all helped me along the way TO a career though, which is what I think's important.