In January, I noted that although the Yemeni Houthis are certainly radical in their rhetoric, Zaydi Islam traditionally is not, and that while technically Shi‘ite in that their Imams must be descended from ‘Ali, they have never identified with the Twelver Shi‘ism of Iran, nor has it generally considered them genuinely Shi‘a. The same is true of the ‘Alawites of Syria, yet today both ‘Alawites and Houthis are loosely aligned with Iran's geopolitical goals (though the links between the Houthis and Iran have more often been asserted than demonstrated).
Iran has been partly responsible for this, but the readiness of the West to accept the narrative of an "ancient" enmity between Sunnis and Shi‘ites, some sort of inexorable clash, has also helped reinforce a regime narrative on the part of Sunni majorities who want to paint non-Sunni minorities as Iranian-backed fifth columns. This narrative has already led to a tendency to paint the conflicts in Iraq and Syria not as complex fractures along complicated lines but as a Sunni-Shi‘ite dichotomy. (The only reason this oversimplification has not been extended to the equally complex conflict in Libya is that there are no Shi‘ites to speak of in Libya.)
The danger is that the more the world accepts the dualistic view, which to some extent reinforces both the Iranian and Saudi regimes' dueling propaganda, the more the various regional conflicts with their complex historical, social, economic, ethnic (and yes, sometimes sectarian) roots, the more these local conflicts are merged into a regional general war, and the sectarian dualism becomes a self-fulfilling prophecy.
On the Houthis, let me note that back in 2009 I was already blogging about border clashes between the Saudis and the Houthis, though accusations about Iranian support were just beginning.
I keep hearing the war in Yemen, which is complex (consider the role of ‘Ali ‘Abdullah Salih, old friend of the Saudis, new friend of the Houthis), described in simplistic ways which see broad geopolitical motives behind people fighting for quite different motivations (power, tribe, ideology). If one side misinterprets the motivation of their adversary, disastrous results are inevitable.