True, but invalidated by burner and jailbroken phones which are widespread in China. They can definitely catch somebody with a concerted effort but I'd be surprised if the average Chinese teenager couldnt figure out how to make a burner email
I think the problem is the majority of people don't know that airdrop isn't actually anonymous, sure there are workarounds but it doesn't matter if 99% of users don't follow them.
There are markets in China where you can buy all the parts super cheap and build your own iPhone. It's like nothing you'd ever see in the western world. Hundreds of stalls all selling an individual specific selection of phone components, and if you ask for something they don't have, they'll recommend their friend's stall to you.
Apple have sold billions of iPhones. All those second hand "recycled" parts go somewhere.
An iphone can be bought and emails can be registered without doxing yourself, so this info isn't strongly tied to your identity the same way a phone number is.