Bitcoins can exist without exchanges, but would you support the argument that the existence of exchanges are among the factors facilitating the popularity and accessibility that people have to bitcoins?
My brother the existence of exchange in the crypto ecosystem space helps a lot in the distribution of bitcoin in the world. Exchange make things easier for the industry, if we use peer to peer, most of us can't even sell or buy 0.0009 BTC a week because it is not everyone accept bitcoin in the locality. P2p can not be seen in everyday and everywhere but with the exchange platforms every day and anytime one can buy and sell. So exchange platforms means a lot in the cryptocurrency ecosystem.
The centralized exchange platforms, the ones I know do not charge transaction fees but the decentralized exchange platforms charges transaction fees. Though all have there advantage and disadvantage