The Divination subject in Hogwarts is practically a copy of the most common muggle divination practices like:
- interpretation of dreams
- reading the future in tea leafs
- palm reading
It is also exactly as effective as the muggle practices - most of it is either pure fraud or fraud mixed with generic predictions that are very likely to come true.
This is in deep contrast with other muggle legends/imaginations that are actually true in the wizarding world. Examples:
- Muggles depict witches flying on brooms - witches and wizards actually fly on brooms.
- Muggles have a legend about the Philosopher's Stone - it actually exists.
- Muggles write stories about dragons, Veela, Leprechauns, Unicorns etc - they also exist.
Divination is an exception of still being a fraud.
Did JKR mean something special with that like making a joke on the actual "divination" practices?