The serial number matches mine. I suppose they could have scratched it off and repainted it, but that seems doubtful.
If the laptop had originally had Activation Lock enabled, the unintended recipient would not have been able to do this, and as a bonus, the location of the laptop would have been trackable.
So, I don't think they had to swap the laptop out for another Activation Locked laptop... they probably locked it themselves, whether intentionally or not.
Where did "90 times" even come from? I can't find that number documented anywhere in regards to Activation Lock, even googling specifically for that number in case there were anecdotes online.