I'm of a mind that bits, in and of themselves (most of them anyway), are no more dangerous to a horse's mouth than a mouthful of soft grass. I couldn't care less whether a person rides their horse in a simple snaffle or a standard curb bit or a spade bit, so long as they have the knowledge to use it properly and the horse has the appropriate training to respond to it then all's well with the world.
I honestly don't understand why there are so many people in this world that seem to think that bits inherently cause pain and bitless is inherently kinder and all
horses would prefer to "not have a nasty hunk of metal in their mouth".
I don't know whether they are just not educated enough to realize how much their hands
affect how much pain/comfort the horse feels or whether they have been so brainwashed by the kook-aid of some ignorant hack of a NH trainer that they just can't think for themselves anymore.
I've seen lots of people ride bitless because they claim that it's so much "nicer" to the horse, yet they have zero hand control and are constantly bopping the horse in the face. The first thing that pops through my mind, though I usually don't say it, is that it would be a hell of a lot nicer if they would learn how
to ride instead of depending on tack to cover up their shortcomings as a rider.
There is one popular online "trainer" (I won't mention any names, but there are probably lots of folks that can figure out who I'm talking about) that advocates bitless because it's nicer to the horseys. The way that said person rides is about like a 5 year old kid that's never seen a horse before. Said person flops around on the horse's back and is constantly bumping/pulling on the horse's face. I would never dream of treating my horse's mouth the way said person treats their horse's face with that rope halter or bosal on there on a common, every day ride. Sure, there are times when a trainer/rider has to get firm with a horse to remind them that they need to listen, but there's a universe of difference between someone with good feel getting harsh for a moment and someone with no feel hanging off the horse's face.
People just can't seem to fathom that it's not the headpiece that you put on the horse that gets results, it's the training that you put in their head. You put the right training on them and you can ride them in anything. But you can almost always tell the horses that are lacking in training and the riders who are lacking in ability because they are the ones that go around in a double twisted wire combo hack-a-gag with 8 inch shanks and a super tight tie-down or a long shanked curb bit run through a training fork adjusted so tight that it pulls the horse's head down between their knees before they get any relief.
The majority of riders would do well (and be better horsemen) if they had to ride in something no more powerful than a simple snaffle or leather sidepull because they would have to learn how to teach
the horse instead of just overpower him with some nasty piece of headgear.
And yep, I'm talking to folks who use bits
AND the folks who go bitless