While I do agree with your point, I think we also both agree that things like grammar and punctuation matter. For example, this sentence as written actually lumps 50 Shades of Grey with flawlessly written prose while I believe your intent was to say it is poorly written.

The sentence should be:

This is why poorly written books can fly off the shelves, e. g. 50 Shades of Gray, and flawlessly written prose can…

Or even better:

This is why poorly written books can fly off the shelves — like 50 Shades of Gray — and flawlessly written prose can…

My husband Paul is teaching a class right now on mechanics and their usage, and the point of solid mechanics is to produce prose that reads swiftly and smoothly to create the hypnotic page-turning effect of a good read.