The essential reason that front-end development "should" be easier than back-end development is that back-end development is fundamentally algorithmic in nature and requires languages powerful enough to solve any solvable problem in computer science, while front-end development--and we really mean layout here--solves the limited problem of placement, layering, and coloring, and only requires a commensurate level of syntactic power for its implementation. I guess my point is that the front-end, or at least the layout portion of the front-end that CSS purports to solve, is so obviously so much less complicated than the back-end that you shouldn't have to point that out in order to deflect the accusation that it's just a naive expectation.
I realize it was probably tongue-in-cheek, but if anyone defends the complexity of CSS by equating it to a jobs program for web dorks, they've just ceded the point that CSS is improperly designed and needlessly complex.