I am a beginner rider.....so, definitely couldn't do it....My only bit of knowledge (and some may disagree) about this question is that it's good to keep in mind that riding bareback is actually harder on the horse. A saddle serves to distribute the weight off of the horse's spine...when bareback, obviously then, you've got your dead weight right there on the spine.....from what I've read, it's best to ride bareback for only short periods of time.
I sort of half agree with this. I think that there are some horses that can only take bb in short periods no matter what. But I think there are also horses that can do fine either way, some start out that way and others need to get their topline built up a little (like my girl :)) but if you think about it, an english saddle is pretty much the same as bb, weight placement wise, yea? And you also use your legs to lift yourself up. Its not so much butt as it is legs and thighs. Occasionally i'll relax and be on my butt as a standstill, but my girl knows when we're about to get moving because she can feel me switch to my legs. Especially when we're about to canter. Half the time I don't have to ask, just get set up for it and she know.
As long as you sit in the right place and in the right position the horse should be fine. I actually notice my horses move more free when I ride bb.
I think its always going to be a matter of opinion and a debate among horse people :) but keep in mind too that horses aren't all the same, and some can do while others can't. And maybe those that think bb hurts the horse have mostly been around horses that can't really take bb. Or not. It could just be their belief and opinions
Thought i'd put my two cents in
i'm currently working on building one of my mare's topline because she can take long bb rides.... but I can't take her withers
whereas my other mare has a nice flat back and low withers. Smooth as butter that girl!....... unless she's bucking.....
but hey.... I can still stay on so that counts for something
Stupid things on a horse. Its what makes us different from people that can walk without limping