Hard drives store data as magnetic fields, and also contain powerful magnets to allow the read head to move around quickly, so there’s a decently high risk of damaging data when transplanting a platter to a different drive or replacing components within a drive. Also, even if that doesn’t happen, modern drives really need to be opened in a clean room as the head floats a very small distance above the platter so the tiniest bits of dust can wreck the surface of they end up in the gap. For some drives, even that isn’t enough as they don’t contain air, they contain helium. Of you want to be sure data remains intact, opening the drive should not be part of your plan. It’s only a good idea as a last resort when you don’t have a more conventional way to recover something.