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?
I believe you're referring to the centralized exchange with this topic because you just saying exchange could mean both decentralized or centralized exchange. If you were not referring to any specific exchange but speaking on the fact that exchange in general has brought about a major contribution to the popularity of Bitcoin then that's accurate because without the exchanges there won't have been a means to exchange our assets to fiats or other cryptocurency.
The availability of exchange convince many investors to invest in Bitcoin because now they don't have to trust some unknown individual to send them there coins or money when they want to sell or buy Bitcoin. They can just trust the system which they're using to execute the trade successful.