It's part of the business model - each FB user generates so little revenue for the company that you can't afford to offer anything resembling "real" support channels. The company is massively profitable by sheer scale - by making a small amount of money per year off of a vast number of users.

This applies to Google as well - or really any ad-based engagement-centric business. Your individual users aren't worth enough to have human-intensive labor assigned to them, hence heavily automated support channels and little to no ability to ever have something processed by a human.

One of many reasons I pay Google to host my email rather than use a free Gmail - when you are generating a non-negligible revenue stream suddenly companies' willingness to answer emails and pick up phones increases.

When it comes to FB there's often the pithy "when you're not paying for a service you're not the customer, you're the product" - which is a simplistic take. In this case though at the very least this is true: "when you're not paying for a service your support needs are dead weight".