Cryptocompare API is not updated
These aggregating sites are just hooking up to every exchange API and querying the data and then dumping it in a database. You could do the same, it's a decent amount of work and costs money to run the server.

For example, Coinigy's API is hooked up with just about every exchange and pair, it is a paid service. I have no affiliation with them. This is only an example.