dirksche From what I understand (and I could be wrong), when your device's wifi communicates with a router, the mac address of both devices are constantly sent back and forth between the two devices as part of the communication protocal. So each packet of data transmitted contains the sender and recipients mac address (random mac or real). All other devices nearby also pick up all communication from those two devices, look at the macs, and if the message is not for them, then they ignore it.
This means that your real mac address will be picked up by other devices and associated with your home address (can be done very accurately by google through other user devices). Your home address is already very likely compromised through various online sources (shopping sites, government emails, etc) and associated with your real identity already.
Then should that mac address ever be seen anywhere else (by accident or otherwise), it will be recognize as you on the move.
If this is true (And i'll leave it up to you to decide if this is true or not), then... why risk it to begin with? Why not just use random macs?
There are occasions when you really have to use real mac address because of technical limitations. If not, best to just use random.
If I'm not mistaken of course.
There are also other scenarios that the real mac could be exposed and used against you, which for the sake of keeping this short I will not get into. So why build up a visible location history with that mac address to begin with?