The fact that you are required to pass ?accept_data_loss=true to that API should tell you that this is completely false.
Yes, things go wrong, that's why you must set up snapshots.
Dangerous tools like elasticsearch-node and the dangling indices API exist for cases where things go so badly wrong that data loss is inevitable. They are not awesome at all, they are a last resort for when things are desperately broken. They don't really "fix" anything and if you use them as a matter of course then you will eventually lose data as a result.