As someone who has never used Salesforce nor hubspot. What are the core features that has people using these services? Is it just the integration between all the different areas where customer data lives?
Where customers do use the features and integrations it’s often a giant mess that needs a whole separate ecosystem of consultants and “partners” to get the thing working and maintaining it.
Salesforce does a lot more than that
But mostly it's a mix of the integration network effects you mention, cost of reimplementation if you want to leave, and the good old "nobody gets fired for buying IBM" dynamic.
Data querying for creating marketing campaign audiences or generating some reporting reporting.
Little development for landing pages, forms, or custom integrations.
Multiple channels (SMS, push, email) & message templating.
And many marketing stuff like AB testing/fatigue, etc