The attack is pretty brilliant; but it's also not quite novel. Cache-timing attacks aren't new; certainly CPU suppliers should have known the general issues at hand for... at least a decade? See e.g. Colin Percival's somewhat related attack on hyperthreading way back in 2005: http://www.daemonology.net/papers/htt.pdf

Actually exploiting the information leakage isn't easy; and its compounded by the secrecy surrounding cpu internals. So I think they definitely deserve some blame here. Yes, the PoC is new. But the attack surface was widely known more than a decade ago, and they chose to punt the issue onto software; a solution that was unlikely to really hold water.