I don't really have any issue with Yelp's terms of service. After all, user reviews are their backbone so I don't blame them for wanting to make sure that any Yelp review information needs to be identified as coming from Yelp / under certain restrictions.

Wouldn't seem fair if Yelp did all the work and any app or platform can simply piggyback off of it and present it as their own, or obscure where it came from.