You have to be careful when you use absolutes. The fact that I know personally of at least half a dozen examples of now grown boys who were not scarred in any way by their sexual relationship with men proves your point untrue. Even the existence of just the one individual who chimed in on this thread proves you wrong.

Is there a chance that it could cause harm? I doubt anyone would disagree that there is.

Does it always happen? No.

How high is that chance? we don't know

Is the risk worth it? each person must answer that for himself.