Niantic announced in their Pokémon GO > FAQ > Submit a ban appeal:
Your account will be permanently terminated for violations of the Pokémon GO Terms of Service. This includes, but is not limited to: falsifying your location, using emulators, modified or unofficial software and/or accessing Pokémon GO clients or backends in an unauthorized manner including through the use of third party software.
For the first three reasons, I think all you and me agree. But for the fourth reason (accessing Pokémon GO clients or backends), it seem including check iv using third party software/web service; so I already removed my intro videos about.