Well, there you go, fanish... I can find some information on anal sex causing permanent damage, but I also found that I can find more that says if done carefully permanent damage can be avoided for the most part. I can also find a lot of information on anal sex actually being pleasurable.
So, I guess you're wrong.
People do willingly engage in anal sex. You can't and have no right to tell these people who are willingly engaging in anal sex that they do not feel pleasure. Whether they feel pleasure or not is up to them to decide.
I personally think there's no pleasure in S&M, but I respect the people who find pleasure in S&M and engage in it. I have no right to tell them they are wrong, they're not feeling pleasure, and they are demented.
I suppose these 'doctors' are among those who take advantage over women for Anal sex, that's why they make it look positive so that women will volunteer themselves....BEWARE LADIES!!!