I was reading an article that uses the phrase "Achilles' heel" to refer to Facebook's acquisition of Instagram, but it was written thus:
My main question is - was this a bad mistake or is making this kind of description in this way a common thing? If so, could you provide examples where others have taken common phrases and lowercased them.
A little more context in case it helps:
Because Facebook is essentially about photos, and Instagram had found and attacked Facebook’s achilles heel — mobile photo sharing.