You are referring to liquidity providers and market maker; they provide the liquidity (in the form of loans for margin trading, among other things), take risk in exchange for market making fee.
An exchange on the other hand is facilitating trades by matching buyers with sellers. At least that's how it works in stock markets. Even if NASDAQ were to become a market maker they would have to spin a separate entity, bring their own funds to provide liquidity. Even then I don't know if it's allowed by regulation.
> Even then I don’t know if it’s allowed by regulation
It isn’t, precisely for this reason. The US Equity and Equity Derivative markets have tried a few times to get approval for initiatives using their already existing BDs (to facilitate inter-market order routing), and in every case it’s been blocked by the regulators as too risky to the underlying business.
The issue here has more to do with the lack of a centralized C&S clearing house in crypto, and is one of the reasons counterparty risk remains such a massive issue there. Having to maintain an account at each exchange, much like you would a BD, and praying things don’t suddenly go pear shaped, strikes me as insane (and is one of the primary reasons I’ve avoided getting involved in the crypto space)
An exchange on the other hand is facilitating trades by matching buyers with sellers. At least that's how it works in stock markets. Even if NASDAQ were to become a market maker they would have to spin a separate entity, bring their own funds to provide liquidity. Even then I don't know if it's allowed by regulation.