If its about plates, explain:
The Arabian Peninsula
Why are the Americas either 1 or 2 continents but nobody says 3?
What's up with India?
The Arabian Peninsula, (India, Bangladesh, Pakistan, Nepal, Sri Lanka, Bhutan, and the Maldives) and Greenland are all considered Sub-continents.
Though if you use the term "subcontinent" in Australia you are almost always referring to the Indian subcontinent.