"Well, we don't run much risk of getting mugged on the local paths here, but mile for mile, hour for hour, I've had many more near-misses, and even falls, on bike paths than on the roads. Loose dogs, dogs on 20' leashes (might as well be loose in that case), kids, riding 50' behind blissfully unaware parents, who can barely stay upright, let alone hold a straight line, walkers 4-5 abreast, rollerbladers, scooters, skateboarders, and vacationers who haven't ridden a bike since they were in their teens. Rent a bike, pedal 3 miles into the wind, get gassed, and then decide to pull a 180 without checking their 6."
I agree on ALL points.
Bike paths, especially the Rails-To-Trails type (in my area, at least) give me great interval practice. and jump workouts. Jumps from 2 MPH back up to 20. Over and over and over. Every mutt, individual and group you describe...and more, you forgot bird watchers and their tripod equipped 20-pound Kowa 120mm spotting scope with digital Nikon attached...makes bike trail cycling an exercise (no pun intended) in keeping your head on a swivel and hands on the brake levers.
I do my best to be considerate and share the trail...