Exchanges dont care for anything else then profit.
They will list scam coins as long people will pay for votes for enlistment.
True exchanges main concern is to make profits and they don't care whether bitcoin will survive or not and exchanges even guarantee for companies who list there tokens that the price will be strong so from every angle bitcoin get negative effects and altcoin ICO project implementation has become a great source of income for many exchanges and also there are lot of people who are feeding from them and that is why more and more new cryptocurrencies are introduced