Interesting, in the case of Ref Token, because it's the only exchange appearing on CMC as REF's markets. And OKeX was actually the site I used a couple of months ago when I sold my small amount of airdropped REF. I'm pretty sure it must figure on some other private exchanges (which would be featured on other listing sites such as CoinGecko.com or CoinLib.io), and of course, we can still trade it on most DEX but still, the move has to hurt the token since CoinMarketCap.com remains the main (and sometimes only) reference to a lot of crypto enthusiasts.

Edit: I just realized​ you mention that only the REF/BTC pair is disappearing which leaves users with the REF/ETH and REF/USDT ones intact.