Depends. It won't help against exploitative firmware or shocker devices, but most USB exploits don't come with zero-day firmware exploits or even require user interaction, which this policy will prevent.
Additionaly, even when attacked with such extreme measures, most users won't try to plug in planted, potentially malicious USB devices if they don't expect them to work.
In organizations where only HID USB devices are allowed, not mass storage? I'm not aware of any reported successes in that environment, although it's theoretically possible (Heck, you could even have your evil HID-presenting SOC USB stick open a command prompt and type in the malware if it detects a long enough lapse in input without an obvious screen lock command).
It is, but if your organization completely forbids any non-HID USB devices, users are less likely to try their found USB stick on a company PC, since they don't expect it to work anyway.
Additionaly, even when attacked with such extreme measures, most users won't try to plug in planted, potentially malicious USB devices if they don't expect them to work.