Salesforce isn't buying a messaging tool. It already has one. It's buying a different default: a signal-first architecture under a send-first product, and fresher context for its agents.
The full argument, including what the integration looks like from the platform team that stitched Marketing Cloud's earlier acquisitions to Salesforce CRM, is in Salesforce Just Bought the Signal. Why the live behavioral record matters more than written context is in Context Is King. Written Context Is Rented.