You’re right, it’s poor general advice; normally batteries function as they should with a few hours in a charger. In that case I would not recommend discharging a battery as it harms the overall lifespan of a battery.

But when things aren’t normal, and it’s an issue with battery capacity not displaying properly, and charging to full didn’t fix it, discharging is a reasonable next step to be taken before getting a new battery or checking fuses. If a battery is already in poor health enough that one discharge-recharge cycle makes an appreciable dent in the remaining life of the battery, it has very little time left either way and needs to be replaced soon.

Some more research seems to back this up; advice to discharge batteries when having issues is present in most battery troubleshooting/repair guides, on forums, and in various device manuals. I stand by my original advice to OP given their description of the issue; and I find “Charging to full is completely enough to recalibrate the monitoring circuit.” to be demonstrably untrue in many situations.

Given all that, and multiple personal experiences with issues being fixed by discharging (and not by just charging), frankly I don’t see my thoughts on this changing much and I’ll continue to use the method as a troubleshooting step when restoring and fixing devices as long as it continues to work. You’re free to give whatever advice you wish, and I’ll do the same, but I don’t see much point in continuing this discussion.