Cynthia, people who breed dart frogs are VERY serious about them! Just as we are about our snakes. You can't just buy a dart frog, take it home THEN set up the cage. They are much more demading than that. You have to put the cage together, get the moss growing and have the fly cultures all ready to go BEFORE you buy your frogs. These people deal with "impulse buyers" all the time, and after a while it gets tiring to be polite to everyone. They like to talk to people who are serious about the hobby. To her it probably looked like you were another "ooh neat, these are pretty, I'll take these home with me." You probably should have just asked how to go about getting the cage together so you could get the frogs eventually. Work a few shows with some beloved species and you'll understand. It isn't easy.....
Anyway, yes, she was right. They are not for beginners even if you have kept tree frogs. I would like to keep these one day, but I am totally intimidated by their care requirements!
Check out
Quality Captives website for more info.