How does it not scale? How does it not make sense? It sounds like maybe you work in a company where everyone is not responsible for customer service/support (which would be very unfortunate) or you're misunderstanding what customer service/support actually is (which I hope is the case).
Your backend developers shouldn't be answering phone calls from customers. That's the job of the helpdesk. But if the helpdesk doesn't know how to fix a problem, they should forward the call or the ticket to the developer. If something is messed up in the database, the helpdesk should have the ability to put the customer on hold, call the developer, and have them make the required change. If the documentation doesn't match reality, the helpdesk should have the power to get the developers to update the documentation. The helpdesk should be analyzing tickets and sending reports to development teams with the mindset that it is the responsibility and the expectation of the development team to make sure these calls stop happening, or that the helpdesk is empowered to resolve them without escalating a ticket.
That is a culture where customer support is everyone's job. If the development team is under no obligation to respond to ticket escalations, that is a toxic support environment. If development is under no obligation to reduce the helpdesk's call volume, that is a toxic support environment. If there is no helpdesk to call, or the helpdesk you've called has no direct line of communication with all of the supporting teams across the entire company no matter their role or function, that is a toxic support environment.