We write bespoke systems in PHP, usually where the job is specific to how a business runs: a booking process that has to talk to whatever the office already uses, a system handling a scale of records that ordinary plugins are not built for, or a routine that runs each morning and reconciles what two other systems think is true.
The advantage of building it is that it fits, and it keeps fitting, because it can be changed as the business changes. More than one system we built has been running for twenty years, with upgrades along the way as the technology and the business moved on, and it still belongs outright to the company that paid for it.