Reading this thread, I am inclined to agree with you. However my own experiences were the opposite. I've been with women twice, the first time went okay, the second one was a disaster of epic proportions. The second one I could not penetrate her at all. She had to go to a dr. to have her hymen surgically opened because it was unusually thick. My size wasn't the problem - no size was getting through that. With anal, having had a rough first time I have always been a slow and easy kind of guy the first time I am with someone, especially if it is their first time doing anal. Fingers, tongues, massage, lubes, whatever it takes to get to our destination. As I noted there are times when I can't do as deep, but that doesn't mean we can't get it done in a good way for both of us.
for me it is about listening and respecting what is on a partner's mind. When they say, "Hey, I've never done anything like that," or words to that effect then it is time to change the pace and work with them to make ourselves happy with the experience.