I work with both enterprise software and in house teams. Each path has its pro and cons. As you put it costly CRM might not be fulfilling its purpose. And the two biggest points in favour of in house are cost and bespoke nature of solution.

Building is only one part. Maintaining and using/running is another.

Onboarding for both technical and functional teams takes longer as the ERP is different from other company. Feature creep is an issue. After all who can say no to more bespoke features. Maybe roll CRM, Reporting and Analytics into one. Maintenance costs and priorities now become more important.

We have also explored AI agents in this area. People specific tasks are great use cases. Create mock up and wireframes? AI can do well and you still have human in the loop. Enterprise level tasks like say book closing for late company ERP? AI makes lot of mistakes.