A simple magnet will not destroy the data eithe
I can’t remember refering to just a “simple” magnet however, when I say strong neodymium magnets, I’m not refering to rattle magnets either.
It’s simple to open up a hard disk and remove the patters and destroy the platters by said method does work if done properly. Even a drremel wire brush attachment will do the same, but I guess it’s how far you want to go and who your protecting the data from and whether formatting and binning or formatting and just removing the platters is enough for security of mind. After all the average tip thief woudn’t beable to recover any data once formatted.