I am the Lord, and there is no other.
I form light and create darkness;
I make well-being and create calamity;
I am the Lord, who does all these things.
This fits the question God asked through Amos:
“Does disaster come to a city,
unless the Lord has done it?”
Then there’s the whole thing with Egypt and all the plagues.
God doesn’t need to do things to keep Israel from thinking other gods were more powerful; indeed He did things to Israel that everyone in the ancient near east would have looked at and decided that YHWH was a loser! The biggest example is the Exile; defeat in war was recognized by everyone as indicating that the losers’ god(s) were weak – but God flat-out claims that He sent Babylon against Jerusalem, just as He sent the plagues against Egypt, just as he sent fire on Sodom and Gomorrah.
So we have the problem that God is recorded as sending calamities on people, including His own people. One way out is to say that was the claim the writers made but they got it wrong, or another that He was just speaking in terms the people would understand, or the interesting one you gave.
But at the root of the claim
I make well-being and create calamity;
I am the Lord, who does all these things.
is God’s taking responsibility for everything that happens in His Creation.
I don’t particularly worry about it. I presume you’ve heard of the trio “the world, the flesh, and the devil”? That listing has the devil in the right place – the least of our worries. I just consider that God is the potter and we are the clay and try not to squirm or protest when He shapes me.