In a nutshell: When it comes to using trackers for stalking people, there has not been any data showing whether it's really a problem or just that media has been paying more attention to it. While there are no formal studies on the activity, a recent survey of law enforcement records preliminarily shows that it's more common than we think.
Motherboard recently requested incident reports from multiple police departments that specifically mentioned Apple AirTags. It received 150 documents involving the device spanning the last eight months. One-third were stalking-related. Most were from women, with only one man reporting his ex had used an AirTag to stalk him. The device was planted in the victim's car in half the incidents. Most of the other reports were robbery- and theft-related.
Although these stats seem to show a significant amount of incidents involving AirTag stalking, it is something that has not thoroughly been looked into before. There is no other data to compare it to, and nobody has looked even further back to see if other devices have been used like this before AirTags came along. Is it an issue exclusive to Apple?
When Apple initially announced AirTags, it touted its anti-stalking security features. Until then, the media devoted very little, if any, time to such coverage. Using other trackers like Tile to stalk people never made headlines, even though it has fewer security measures in this regard.
Motherboard's study raises more questions than it answers. Is it an instance of Apple calling attention to a nonexistent problem and giving bad actors the idea, or just a matter of the media paying more attention to it now that it's been brought up? Either way it seems like Apple let a cat out of a bag. More thorough studies could show whether tracker stalking is on the rise and if the problem existed before Apple brought it to public consciousness.