This started with wearing and ended up with waving but thats cool - let me give you an extreme example.
In a certain country years ago a political party was formed and they appropriated a symbol from another religion to represent the party. Early on, all good, the party gained control of the country and was one of the most popular parties in history. Economy was ok, education was good, social welfare was good, people had jobs and everyone was happy. Wearing that symbol became a source of pride in that party. Now fast forward about 10 years, members of that party were being hunted down and executed. That symbol was vilified for evil and countries to this day have banned it.
And that symbol was the swastika.
Yeah its extreme. But how many of the swastika wearers deplored what was happening but said nothing? Because they were part of the herd.
As I said before - extreme example. But for something that really has no point, why create the possibility, no matter how remote, of creating some ideology?
Flags belong on flagpoles. If you wanna do your wavy at an Aussie day bbq - all good. But wearing it? Nah... step too far.