You're misinterpreting

Requiring docs isn't the cause of the problem. It's the lack of enforcing quality. The difference is that you're looking at the metric and seeing Goodharts Law in action while there's nothing preventing you from going beyond the metric. That's the real issue is that metrics only take you so far. No metric can be perfectly aligned so it's up to the people who are evaluating the metrics to determine if the letter of the law is being followed or the spirit of it is. If you do the latter then yeah, maybe some functions will be left without docs but you also won't hasn't those tautological docs either. If you only care about the letter of the law then you should expect the laziest bullshit as Goodharts Law always wins out.

Stop reading too much into metrics. Metrics are only guides