You can listen to whoever you want, I'm not telling anyone what to do, just sharing thoughts and engaging in discussion. I'm also not inclined to listen to random posters that can't maintain civil discourse. But I can respond politely anyway.
You do in fact see MMA fighters break fingers fairly often. This is even with some support from their gloves and tape jobs. And it does affect their overall performance. They don't generally quit because of it (unless the doctor makes them), but it does affect them. I like the "rub some dirt on it" direction, I use that myself. However, if you can avoid it through training methods, why not.
As far as asking aikidoka about fighting goes, that depends on the focus of your training. If you do Aikido for health or other reasons, don't worry about it. But if you have any expectation at all that what you are learning could be useful in a self defense situation, then you should think about these things. Again this is an individual choice, choose however you want.
If my response seemed uncivil, I apologize. You asked a simple question and I offered two short, simple opinions from the perspectives your question covered, aikido and fighting. I'm sorry if it came off any other way.
Your previous post mentioned instructors who recommend a method that is at odds with what the founder of our art, his teacher, his contemporaries and some of his most skilled students had to say on the subject. From the aikido perspective, it would probably behoove us all to listen to them as some of these seemingly small things are integral to the art in ways that most of us simply didn't get.
I'm sure broken fingers happen in mma. I'd be surprised if they didn't, though I don't recall ever seeing it happen in matches and I've watched many. I know they are more common in judo and bjj from getting caught in the gi, but that's also in situations that aren't quite fighting but are far more "alive" than what were going to encounter in most any aikido dojo. I've seen a few "real fights" in my day. Lots of grabbing, shoving and whatnot, using their hands like hands, fingers exposed like in normal daily life and I've never seen a broken finger, but that is purely anecdotal.
So IMO your concerns are unfounded, but again that's just my opinion. I don't train fighting, just good hard physically trained aikido that has and hopefully will continue to serve me if needed. The fingers have never popped onto the radar for me as a concern, but I've trained that we for some time. Ymmv.