if you need to bring outside data into smart contracts, there are many centralized solutions.
You can use Oraclize, you can even roll your own small program that makes transactions with the data in it, and run it on a small server you can rent for like a few bucks a month.
No need for a separate token for it.
The thing though is these are all centralized solutions.
LINK is supposedly the only decentralized solution, BUT decentralized oracles are an UNSOLVED computer science problem.
The biggest threat are sybil attacks which basically is one person/one party creating multiple identities to compromise any decentralized reputation system. Think sockpuppets, or fake accounts for farming upvotes/likes.
The only solution LINK has offered so far is KYC nodes, which is not a real solution, and isn’t really decentralized at all (who exactly vets the KYC? them?)
So it’s still centralized, in a way.