Kappy wrote:
You can drag and drop to move as long as you have write permissions on the original enclosing folder, or the folder does not otherwise have a restriction that prevents removing files from the folder.
Barney, a Drag and Drop only moves on the same disk. It copies if transferring to a different disk. That is without the use of a modifier key that enables Drag and Move operation to a different disk.
You really need to read what I wrote, try to comprehend, ask for explanation if needed, and above all, attempt to move an Apple application file out of Applications (for an example of what I am describing).
There is no mention of another disk in the original question, but I explained the default behavior in my follow-on post as both you and iLogger have confused the issue.
Changes in Sierra began the lockdown of certain folders which results in the behavior described by the OP. It has gotten more expansive in High Sierra.
Normal function of the Finder will allow drag and drop to move a file as long as you do not cross volume boundaries. It will further prevent you from moving a file out of a folder that has some restriction on it that would prevent you from deleting the file. In that case it now makes an Alias in certain situations. The command key will alter that behavior to copy the file in the case that the Finder chooses to make an alias.