diskutil is for disks (e.g., volumes) while hdiutil is for disk images ("file system as a file"). They're not two versions of the same thing, so it doesn't make sense to dub deprecating hdiutil as "progress."
replyThe former has been taking the latter’s job for years now.
replyNobody really cares that they were originally for separate things.
What are you talking about? You can't operate on disk images with diskutil outside of the few commands diskutil image gives you. For example, if you need to check whether or not a disk image is encrypted, you can use hdiutil info and hdiutil isencrypted. If you use diskutil image info, you may be prompted for a password, which doesn't make sense to handle in a program.
replyA disk image is not just a fancy disk. Disks and disk images operate on different planes, which is why the distinction between diskutil and hdiutil exists.
If diskutil actually did everything OP looks for that was available in hdiutil, that's correct. If you read the post though, you'll see that diskutil has many limitations compared to its predecessor.
replyProgress is when we make things worse just because we can.
replyUsername relevant as always.