Just my opinion, but I think that Barry was just the catalyst. The disrespect for the Anthem is actually part and parcel of the entitlement generation, who are "inconvenienced" and otherwise lazy to haul their butts out of their seats long enough for the Anthem to be heard and sung.
The "inconvenience factor" causes the perpetually lazy and clueless to start questioning why the Anthem is performed to begin with. Utterly failing to understand tradition, respect, and acknowledgement to the country that provided them the opportunity to watch a sporting event without starving, or without fear, they show their dissatisfaction by flipping everybody else the bird.
This is what happens when every want is spoonfed to the perpetually unsatisfied. They start asking questions, and those questions become outright defiance. Finding yet another way to shock the general populace, the Kaepernicks and other jockbreaths now find themselves celebrities, and the piling on continues.
These turds should be flushed with power washers, right out to the sewer from whence they came.