The barn is kind of a unique situation.
Much of our human interaction takes place at work, school, or shopping, which are public but all have institutional constraints. Or at home, where you get to choose who you invite. At purely social events you can move on to “freshen your drink” or “say hello to Bob who just arrived!!” when you are captured by a bore. Hobbies and sports can be solitary (like jogging) or group oriented, where the group may be able to either enforce proper behavior or exclude bores.
The adult barn is a shared hobby space where you are working alone but parallel to other members. There’s not a team group or leader to keep folks on track with tasks, and you can’t simply just peddle your bike faster and leave the bore in the dust.
I’m trying to think about other hobbies that set up the same situation. I bet you could have this dynamic in a community garden. People do have it with neighbors sometimes, but hopefully you can move away from the fence or plant a hedge. People do have it with friends or relatives that phone and rattle on forever. But there are ways to hang up the phone. Or screen calls. Another situation could be sitting next to one on a 5 hour plane flight. Yay ear phones and faking sleep.
Anyhow, the obvious shared interest of horses gives everyone at the barn permission to talk to each other, but the lack of institutional structure means that those who don’t self regulate can really go overboard, and you have to do the task that in other situations the boss, teacher, yoga instructor, choir director, tour guide, etc is paid to do and usually has some tactics based on authority to compel task focus.
We actually delegate a lot of managing problem people to these institutional authorities (I say as a college instructor who does pay attention in my classes to keep students on track). But when we are in situations like the barn, parallel participation with no authority figure present, we need to manage them ourselves and I feel like lots of women, in particular, have been socialized to not value their personal time and space. We defer or at least negotiate with men we are intimate with, we are wide open to small children, we also recognize that letting small children chatter endlessly is crucial to their cognitive development, and as long as it’s happy chatter, rather sweet (I don’t have children so I am guessing here 
that happy chatter is happy back ground noise compared to crying and tantrums).
The adult monologue bore is different than a toddler, they take up more space and they demand your attention in a more concentrated way, and the conversation is usually repetitive and stuck, there’s no development going on. Fortunately they are fairly rare, and in many situations held in check by institutional constraints. Most of us don’t tend to invite them into our lives, unless they are family and we can’t avoid them. So it’s likely true that many of us don’t have a lot of experience either recognizing these people early on, or extricating ourselves.
I would say that the more normal, social, well adapted you are, the harder it can be to recognize cray cray of any sort, and harder to deal with it promptly because you just are not expecting it. Your default is normal adult communication and manners.
I’m not sure what it says about me that I automatically scan for craycray every single time I meet a new person, and kind of expect there to be a nonfunctional or maladaptive layer somewhere in them which I want to know about and avoid. The Chatty Cathy monologue bore is something I feel I pick up on pretty fast, even just by listening to folks chatting among themselves.
Anyhow these were some new thoughts I had about why COTH gets a continual stream of queries about how to handle obnoxious or difficult barn folks. I do think the situation of parallel hobby tasks with no immediate oversight throws us into having to deal with problem people directly without any institutional controls, and also that the “free space” of the barn can free problem people up to be less regulated. It’s pretty clear to me that many of our barn members are at the barn to talk endlessly more than to ride.
