I think some of our Idiocracy problems are due to nothing more complicated than the fact that modern technology and gadgetry give people the option for constant and rapidly changing titillation.
I prefer to believe that modern life allows stupid people to reproduce instead of being eliminated from the gene pool.
Think about bike helmets.
When most of us were children there were no such things. Life did not come with padding at all. We were forced to consider the potential outcome of our actions and if we chose incorrectly we might have been killed. Bike helmets have prevented the deaths of countless idiots who then grow up to become government dependents and, unfortunately, parents.
Lots and lots of modern things accomplish the same outcome: More stupid people live who should have died. And when stupid people live they vote. And when they vote we get stupid community organizers for president. And they also re-elect stupid senators and congressmen. Sheila Jackson Lee could never be elected, let alone re-elected, in a less stupid world. That she is a multi-term congresswoman is all anyone needs to know about the intelligence of the electorate. Where did these stupid people come from? A lot of them didn't die from stupid decisions made throughout their lives...decisions that would have killed people in an earlier time.
On the other hand...modern life has introduced a few things which do actually end up killing off lots of stupid people. Recreational drugs come immediately to mind.