...If the drive is formatted APFS each file's data is intentionally scattered all over the drive which makes any attempt to re-assemble the contents of any given file impractical if not impossible.
Isn't that the case with an SSD formatted HFS+, too?
Yes, but as I understand it, not to the same extent as in APFS. For one thing there is an additional
virtualization layer in APFS. For example you can have multiple APFS volumes on a drive and theoretically each would have the maximum capacity of the drive available to it. Roughly analogous to having multiple sparse disk image or sparse image bundles on an HFS+ volume.
