The WordPress-versus-custom debate gets treated as a technology argument when it's really a business-fit question. WordPress (and platforms like it) is a mature, well-supported way to build content-driven websites quickly — corporate sites, blogs, most e-commerce stores. It comes with a large ecosystem of themes and plugins, and updates to content don't require a developer.
Custom-built websites make sense when the site needs to do something that off-the-shelf platforms don't handle well — tight integration with an internal system, unusual functionality, or performance requirements that a plugin-heavy WordPress site struggles to meet. Custom builds also avoid the maintenance overhead that comes with managing dozens of third-party plugins, each a potential security liability if left unpatched.
For most corporate, institutional and small e-commerce websites, a well-built WordPress or WooCommerce site is the pragmatic choice — fast to launch, easy for non-technical staff to maintain, and cost-effective. The mistake isn't choosing WordPress; it's choosing a poorly built WordPress site stitched together from a dozen incompatible plugins, which is often slower and less secure than a lean custom build would have been.
The honest answer, when a client asks which they need, is: it depends on what the site has to do in year two, not just what it needs to do at launch. A good technology partner will ask that question before recommending either.