I wouldn't doubt the knowledge of the PT's based on their ages alone. Sometimes being newer anywhere in the medical field can be a good thing because they are up to date on newer things, where older practitioners have to choose the right continuing education classes on their own to stay on point.

I think this is the perfect example of the pot calling the kettle black, but sometimes the point of PT is to build you up to the best you can be, while realizing you have limitations

I think it's a good idea to talk to your PTs about what kind of activity level is reasonable for you... like what is a reasonable distance for you to walk.