That gives you a lot of articles -- or a lot of copies of the same article -- written right after the election. Later on, that view was called into question.
In reality, the exit polls showed that a record 35% of all voters who cast ballots in 2012 identified themselves as “conservative” – which helped to explain why Romney drew more than a million votes more than John McCain, while Obama got nearly four million votes less than he did in 2008. For the victorious George W. Bush in 2004, conservatives amounted to only 34% of those who voted, so their percentage of the electorate actually increased for Mitt Romney. The great Ronald Reagan managed to win a landslide in 1980 with an electorate that included only 28% of self-identified conservatives. Source
It's hard to say just who is a conservative and who isn't, but it doesn't look like more ideologically committed conservatives stayed home in 2012 than in 2008.
Right. There’s no statistical evidence whatsoever that enough conservatives stayed home to change anything, much less flip a state.