The sentence is a sample one form LDOCE:
We had to hold the tent down with rocks to stop it blowing away.
Why not "to stop it being blown away"?
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There is no reason why you can't use your suggestion instead. They mean the same thing.
(Although, in both examples, it would be more common to hear stop it from blowing away or stop it from being blown away.
Stylistically, one has more of an active voice, while the other is more passive. But they are both grammatically correct.