[TeaBrain]

Brokers exist as they are providing the service of managing and routing orders to an exchange, which market participants in electronic exchanges wouldn't be able to interact with otherwise, without having a colocation spot on the exchange and knowing FIX protocol. Retail traders don't know, don't want to learn, and really have no reason to learn how to route unmanaged orders via FIX protocol. If you want to directly interact with an exchange you can do so, you'll just have to buy or lease a colocation spot on an exchange first.

Cryptocurrency exchanges are like many FX exchanges. They are not exchanges like the regulated stock, futures and options exchanges are, but are more like decentralized trading pools with unsynchronized order books, which are opaquely operated by a single broker. In crypto exchanges, it is not that there is no broker, but that the exchange and the broker are the same entity. There is no standardized protocol to route independently managed orders directly to crypto exchange servers. There's usually no way to directly interact with the exchange server at all.