Every time someone does that, multiple people pop their heads up and talk about blatant ripoff (even when credit is given).
Sure, we have Amazon as e-commerce and this is a resume, where the other case are both essentially blogs. But, you have two cases of people using the design of someone (or something) else for their own purposes.
And, the argument that "people using the svbtle theme are trying to leverage the popularity of svbtle.com to gain legitimacy" is likely the minority. Most people like it for it's cleanliness/simplicity.
It's the same reason why Android handset manufacturers got accused of "ripping off" the iconic design of the iPhone, whereas in an earlier era people thought Salvador Dali was being artistic when having the considerably more original idea of designing a telephone handset to look like a lobster.