The Shia-Sunni conflict in the Middle East is really just about politics

A recent article on Vox.com does a pretty good job of explaining the ever-shifting sands of Middle Eastern politics, and in particular the place of Shia-Sunni religious differences within it.
The Shia-Sunni split originally occurred back in the year 632, when the prophet Mohammed died without leaving a surviving successor. This led to a schism between the followers of Mohammed's companion Abu Bakr, who was elected first caliph by the Muslim community after Mohammed's death, and the followers of Ali ibn Abi Talib, Mohammed's cousin and son-in-law, who some believed was explicitly named by Mohammed as his successor. As a group, Abu Bakr's followers came to be known as the Sunnis, and Ali's followers became known as Shiites.
Both Sunnis and Shiites are of course Muslims, followers of Mohammed, and their religious differences are actually few, probably much less than in the later Christian schism between Catholicism and Protestantism (which itself led to significant bloodshed and strife). Sunnis have held power throughout most areas of Muslim history, with the Shias as their ever-present opposition. Today, some 85-90% of the world's Muslims are Sunnis, and they represent a majority in most Muslim countries and communities throughout the world, with the notable exceptions of the Shia-majority countries of Iran, Iraq, Bahrain and Azerbaijan (plus a sizeable minority in Lebanon and Pakistan).
So, given that the schism arose nearly 1,400 years ago, largely out of historical and political differences rather than religious ones, and given that Shia and Sunni religious practices and beliefs are only differentiated by a few, relatively cosmetic, elements of ritual and custom, why does it appear to have such an important influence on various Middle Eastern struggles? Among others, it seems to be at the root of the current conflicts in Syria and Iraq, and the recent (and escalating) face-off between the Sunni powerhouse Saudi Arabia and the upstart Shiite power Iran.
But, in reality, these conflicts are not religious in nature, but purely political.
Both Saudi Arabia and Iran are using the ancient schism as a tool to further their (very modern) political aims. The Saudi-Iran cold war has been heating up since Iran's Islamic revolution of 1979, and has much more to do with Iran's staunchly republican opposition to Saudi Arabia's monarchist traditions than it does with ancient sectarian differences over who should have succeeded the Prophet Mohammed. Prior to the Iranian Revolution, the two countries managed, for the most part, to co-exist quite peaceably.
Iraq is another case in point. For much of Iraq's history, Sunnis and Shias have lived generally peacefully, often side by side in mixed neighborhoods. Under Saddam Hussein, the Shiite majority population was dominated by a powerful Sunni minority, which managed to maintain a precarious balance within Middle Eastern power politics. When the US toppled Hussein in 2003, that balance was destabilized, and Iran, Saudi Arabia and a weakened Iraq all tried to assert themselves, using Shia-Sunni sectarianism as a convenient proxy for their political designs. When the Arab Spring of 2011 began upending governments across the Middle East and North Africa, both Saudi Arabia and Iran again tried to fill the vacuums and assert their own influence, often supporting violence and amping up Sunni-Shia sectarianism in order to promote fear of the other side.
Much the same thing has happened in Syria, although in Syria's case a majority population of Sunnis are ruled by an Alawite Shia minority, which dominates the country's government (including President Bashar al-Assad) and its key military positions. What was initially a secular internal civil war of a disenfranchised people against a tyrannical despot, though, has gradually morphed into a sectarian struggle, with Iran and Saudi Arabia once again interfering and arming their own interests.
The political turmoil in the Middle East is routinely reported, even in the most reliable of outlets, in terms of a religion-based struggle between Shias and Sunnis (Jeffrey Simpson's article in todays' Globe is just one example), but I just don't believe that is appropriate. While I often rail against religion in these articles, here is a case where religion appears to be the culprit, but is actually probably not. Here is a case where religion is actually being cynically exploited by politics. There again, I should also point out that I also tend to rail against politics.