WordPress is the right call when you need a brochure site or a blog that the team will edit themselves without a developer. It's faster and cheaper for typical needs.
Custom development (React/Next.js) wins when you need any level of functionality and maximum site performance - complex integrations, unusual logic, or heavy load, for example.
The mistake is picking the stack before the task is even defined. We start by describing what the site needs to do a year from now, then choose the technology to match - not the other way around.