Probably because reputable exchanges don’t charge extortion fees to be listed (Bitfinex for example).
The whole idea of paying an extortion fee is very 2017.
If we want to raise awareness and come into contact with more decentralised developers then ERC20 is where they are mostly at. With luck we are stuck with dead-end Omni for just a little while longer. Notice how native token DOT of Polkadot is listed everywhere but they did not pay listing fees?
Paying extortion is not the way to go about it, see the exponential rise of DEX volume into the billions as a counter example.