1. Was the feature designed badly? Yes. Friends should be unchecked by default.
2. Did Path call anyone? No. That's a service from phone providers when a text is sent to a landline.
3. Did Path sent texts without permission of the user? No. But the feature was designed in a way that many people just tapped yes and didn't uncheck their contacts.
No?
The permissions screen is shown in the verge article. It's labelled: "Find Your Friends: Path is more fun with friends. Find out who's already on Path."
I interpret that as asking permission to run my contacts against its database and tell me who else is already on Path. Not as asking permission to text people who aren't.
Permission to do some X with a contacts list is not permission to do anything with a contacts list.