I think everyone would agree that it's appropriate to pick up a child if a dog is running towards them barking
I would question how often that actually happens. you said thatall they see is loud dogs barking at them and running at speed towards themand said you carry them through the park, which suggests it is happening everytime that you go to the park/regularly
I've been walking my dog through various parks multiple times a day for 10 years. I have never witnessed that. it's definitely not a regular occurrence
I think it's happened once to my DC and the owner was firmly told by me to sort their damn dog out.
I've seen other dogs off lead and not recalling as well as I would like, but that's not the same as them what some claim on here, where apparently some people can't walk outside without a million dogs bounding up to them, covering them in muddy paws, terrifying the children by jumping on them, and helping themselves to every picnic the Mumsnetter has in the park.
I think some people on Mumsnet are over-dramatic though, not just on the dog topic.
For most daily life situations I tend to think if someone happens rarely/as a one off then the chances are the other person is being very unreasonable, but if something apparently happens all the time then you're the common denominator so either it's something you're doing or your perception is off.