I said this elsewhere in this thread, and I’ll say it again here: what you’re describing is Redfin. They’ve been originating loans for a couple years now, and creating that efficient vertical integration.
Zillow does this at greater scale than Redfin. Coldwell Banker also has an affiliated loan arm of their business (Princeton Capital). The difference is that Redfin is a broker whereas Zillow is not. Zillow has 20x the traffic and reach of Redfin plus the originate mortgages and provide instant offers. Because Redfin and Compass are brokers, they have more legal restrictions on how they offer these services to others that limits their reach