For all intents and purposes, LinkedIn has been a (x) closed and (y) mature ecosystem for a long, long time.
LinkedIn has very few partners of scale that really leverage LinkedIn’s data. 99% are blocked. Intentionally. By design. (And it worked/works).
Everyone has had to deal with LinkedIn as the Mostly Closed, Professional Workers’ System of Record for a long time.
There’s really nothing material Microsoft can deny to other companies that they haven’t already been denied for many years.
And the synergies are limited. This will make no one use Dynamics CRM over Salesforce. No one.