For those people who don’t know, in women the anus is connected to the female vulva pleasure network and so women can experience orgasms and squirting as if their vaginas were being penetrated/pleasured. This is in addition to the nerve endings in the anus area which produce pleasurable sensations. I think its different for men, but not being gay or bi-sexual, I haven’t ever looked into this.
The asshole has evolved to be an extruding mechanism. In order to use it for entry, generally it must be gently introduced to penetration, over time (weeks), with a gentle, caring & considerate person, where each session can take 30 mins or more, of gentle massage, caressing the hole and surrounding flesh and only slightly trying to enter the asshole now and then, with a small finger or "spongy" or soft-ish toy. Its also crucial that the person getting this anal attention desires it and is fully relaxed, otherwise it just won't work. Over time, the level of probing can be gradually increased as the asshole gets used to the regular level of attention. Age matters too. If the person (a woman lets say) is young, this process will typically take much longer than a mature woman, whose bodies generally have loosened up over the years (not always but often/most) and so often a 40+ year old woman will be easier to prepare their asshole and for her to engage in anal sex and fisting. Plus, with mature women who haven't done this before, its something new and exciting to try and which often gets their interest.
Yeah, but look at what's happened to her asshole. She gotta have some serious issues or she will have soon, because she didn't take care of her asshole so far and now its all wrecked to hell. You can fist an asshole for years and not have any serious issues, if you do it right from the beginning.