How it is possible that Byteball is on Bittrex but not IOTA ?
The IOTA developers have said it is difficult. But you can see Bittrex listed Byteball without problems.
For sure, the IOTA devs have an exclusive agreement with Bitfinex. And if I see what Bitfinex do with their Tether-shit it is unbelievable how IOTA devs trust Bitfinex. For sure something is wrong between Bitfinex and IOTA and the whole IOTA-Exchange thing.
An exchange can add IOTA without IOTA devs' permission and even collaboration. IOTA is a new tech and it takes time for the exchanges to code and test.