Why is India seen as a subcontinent of Asia while Europe is considered a separate continent?

I don't get it, both are essentially giant peninsulas on the Asian continent and the mountains that separate India from the rest of Asia are WAY higher than those that separate Europe from Asia. I know that Europe and Asia are sometimes lumped into the single continent of Eurasia but since Europe only has a fraction of the land area of Asia, wouldn't it make more sense to call Europe a subcontinent of Asia?

Why is India seen as a subcontinent of Asia while Europe is considered a separate continent?
Why is India seen as a subcontinent of Asia while Europe is considered a separate continent?
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