The tone, the mean-spiritness, discussing posters instead of issues. Even if you don't start that way, you become what you try to resist as a matter of survival. But some are quite mean.
However, some people just cannot deal with politics due to disagreement and probably avoid it for that reason.
Before you read the “Outside The Lines” report, consider this:
Taping the opposing team’s sideline still isn’t banned; only taping the opposing team from the sideline is illegal.
Also remember this:
Taping the opposing team from the sideline wasn’t banned until 2006, yet the report cites examples as far back as 2000. ~NESN