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?
In my opinion, cryptocurrency exchanges have played an important role in the popularization of Bitcoin.
For the functioning of Bitcoin, the presence of fiat gateways is essential. In the future, the era of Bitcoin dominance over all other world currencies will come.
However, at present, Bitcoin interacts with the traditional financial system (including through trading on cryptocurrency exchanges). Currently, there are new ways of exchange, such as atomic swaps.
The importance of cryptocurrency exchanges, especially centralized exchanges, is gradually decreasing.