Yeah, I can see that. It mostly makes me roll my eyes at the person’s inability to express himself in an intelligent manner. It’s meant to inflame passions, of course, and is successful in doing so for many. I remember being angered by the flag burning when I was in Vietnam, but mostly I remember feeling hurt that my fellow countryment thought so little of my service. In retrospect, that was an inaccurate interpretation of their actions.
I have to say “flag burning”, but that’s because I can see circumstances under which burning a book is merely using for kindling paper whose only other possible use is recycling (it’s not like the world needs a copy of a 1953 2-volume Complete Logarythms) but I don’t think I’ve ever seen anybody burn a flag without intent to offend.
For the US flag, at least, it’s the preferred method of retiring them, actually. There is a lot of ritual involved first though, we don’t just chuck it onto a camp fire or anything.