My customers pay me for the features I am building all into this service... Not to charge them to hook a membership for another company up to it.
Then I have to provide support for Salesforce. Their service goes down, now I have my customers mad at me because part of my service is down.
No thanks.
https://en.wikipedia.org/wiki/Category:CRM_software_companie...
Giving the customer direct ownership of their CRM database is a feature, not a bug. They will benefit from a CRM development team who has dedicated experience and expertise in CRM, plus they'll benefit from the feature and security requests of the other CRM customers. And it will make them less dependent on you, specifically. Which, from the client's perspective, is a good thing.
Edit to add: what's more likely, that Salesforce goes down, or that you are unavailable for some reason?
The parent comment at the head of this subthread specified that the client wants a CMS. That's how we got on the topic of Wordpress to begin with.
I agree that Wordpress would be a terrible platform for building a CRM. But I am dubious that anyone needs a custom CRM. There are literally dozens of commercially available CRMs at all price points and industries.