If I have a soft link in a directory and drag it to a different directory, then what happens, very unexpectedly, is that the target file itself is moved to that directory and deleted from its original location. 

I.e., suppose I have in my home directory a link myfile.txt whose target is /tmp/realfile.txt. If I drag that link to, say, $HOME/tmp/, then what happens is that realfile.txt gets moved to $HOME/tmp/. So /tmp/realfile.txt no longer exists, and the link itself disappears.

To say this is unexpected would be an understatement. If the original file was on a shared drive, it could effectively lead to data loss for other users.

I am reasonably confident it did not always work this way.