Bittrex has been adding new tokens, and EXP hasn't been de-listed. 
Well, they didn't add that many coins...thats why I said en masse.
But, they removed FRK
What surprised me is that they removed MAID recently
There are still lot coins on both Poloniex and Bittrex with lower volume
When Bittrex removed FRK, it wasn't from trading but the wallet. FRK was removed from trading a long time ago.