Sorry, but that's just not true. 10 years ago fares were quite a bit higher when compared to the median per-capita income. There's no way in hell I could find a non-stop transcon for $200 or $250 back then.

You want to know what's clogging the system? It's not the affinity cards. It's the LCCs and the competition they generate. 10 years ago the only major viable LCC was Southwest (and ValuJet if you look back 15 years), and it operated in a fairly limited capacity... it was no match for the legacies overall, and they only competed with one another, which meant that price wars didn't really ever get out of control. Fast forward a few years when LCCs started booming and that is where you get the passenger influx... suddenly, flights were super-cheap and passengers were flocking to the LCCs. The legacies had to drop their prices to compete, and now the fares on many routes are driven by the LCCs, even for legacy carriers.

Now passengers could afford to fly not just on LCCs, but also on the legacies, and since legacies had more flexible and more generous loyalty mileage programs, all of these passengers could now redeem award travel on these flexible programs that frequently had vastly reduced traffic (from only-legacy customers). With the huge influx of low-cost passengers eating into the award travel, the loyalty programs had to change by increasing redemption levels and decreasing availability... that's just the only way they could remain viable as legacy carriers while still dropping fares low enough to compete with the LCCs.

Sorry, it's not the affinity cards that clog up the system. It's all the passengers who demand (and therefore get) low fares. When flying became a commodity that anyone could afford, that is when the system got clogged. The affinity cards are insignificant in comparison.