It would be possible to add this particular bit of information without changing anything that affects compatibility. The only difference would be that some file

It would be possible to add this particular bit of information without changing anything that affects compatibility. The only difference would be that some files would actually be deleted when a delete operation was applied. It is a separate information channel that can be added on top. This has nothing in particular to do with flash vs spinning rust. A copy on write file system for example generates tons of information leaking copies all the time, but could trivially be be changed so that some files did not leak in that way. This is truly one of those issues that exists simply because no one can be bothered to fix it.