Off-the-shelf software has never been better, and for many needs it is exactly the right answer. The problem appears when a business quietly starts bending its own operations to fit the tool — changing how it works so the software stays happy.
When that happens, the tool has stopped serving the business and the business has started serving the tool.
Fit is a business decision, not a technical one
Custom is not about building everything from scratch. It is about deciding, deliberately, which parts of the operation are distinctive enough to deserve a system shaped around them — and which are better handled by something proven and standard.
Technology should adapt to the business, not force the business to adapt to rigid software.