Comment by Neywiny

I think it's about being a configuration management nightmare. If every device has a unique password, you need the decoder ring for serial number to password. However, not all processors have unique IDs. So you either need to find a way to reliably serialize each board during manufacturing and hope it stays (like a sticker/laser/printer/etc) or add a serial number chip which is cost and complexity. It's not impossible, it's just extra work that usually goes unrewarded.