How I sold an old Mac and unknowingly had access to its location for over 3 years

If anything, I’d see this as a security benefit. The way I interpret it is by maintaining this link it would allow someone to track down a stolen device that the new owner tried to purge and make their own. I’d put the burden on the seller if they were truly concerned about privacy as it isn’t Apple’s fault that they tried to give you a feature to locate your device.