Obviously the purveyors of mascots such as Chief Wahoo don't sit around thinking, "How can we hurt Indians the most?" But the child who gets taunted for being a "savage" doesn't know or care about the Cleveland Indians' intent. The racist stereotypes percolate through our culture and cause harm whether the intent is negative or not.
The vast majority of people from slaveowners to minstrel-show performers to the Dudesons thought what they were doing was good or at least benign. Their opinion of their own racist actions couldn't be less relevant. It's like asking someone who abused a woman to explain himself: "I didn't mean to hurt her. I was just having some fun." It's worthless.
Again, this is Racism and Stereotyping 101. What I refuse to entertain is your ignorance of how stereotyping harms people. Until you cite and quote a source other than your own made-up opinions on the subject, don't expect me to take you seriously.
For more on the Irish band, see Battle of the Bands: Gays vs. Indians. For previous demolitions of the "harmless fun" argument, see Deadliest Warrior vs. The Dudesons and Ethical Code for Native Elders Needed. For more on the harm of stereotypes, Why the Media Matters and Stereotypes Teach Natives They're Inferior.