Symbolism is tremendously important. Don't let anyone tell you ever that an issue is "merely symbolic," because we put a lot of store into symbols. American flags, confederate flags, statues of confederate generals. Words are symbolic and we need to be careful to use the right words at all times, those that are "symbolically correct," so to speak. People can go to war, ostensibly at least, over the right to use their own symbolic code, rather than that of the oppressor.
We cannot disparage interest in symbolism, then. Both Trump and NFL players seem to agree on the importance of the flag. There is no position that views it simply as a piece of cloth of no significance. In this sense, revering and burning a flag are acts invested degree of deference to an identical symbol.
Yet we can win all the symbolic battles we want, and nothing will change. Aren't we always told that racism is "structural"? High rates of incarceration and poverty among African-Americans are hugely more significant than some statue of Robert E. Lee. We can ban symbolic expressions of racism all day long and have structural racism run rampant. People who are overtly racist and fascist, etc... are only a small part of the problem.
Yet people seem to only understand problems in symbolic or iconic fashion. It's always some outrage over something someone said. Even a problem like police killing of civilians is reduced to a few iconic cases, when it is really a structural and statistical problem.