And, there are people who cannot read scripture for what it says, and try to over-complicate a rather simple, straightforward principle.
The bigger issue is people teaching unrevealed doctrine.
I'll give you some background on what I am thinking of regarding this verse. John MacArthur put on an anti-spiritual-gifts conference maybe 9 years ago or so. RC Sproule was a guest speaker. They played a recorded message. He was addressing the issue of believers being empowered by the Spirit supernaturally. He went through three passages in Acts-- Acts 8, Acts 10, and Acts 19.
Here were his reasons, as I recall, for why he thought these things occurred- so that God could show he was accepting the Samaritans in Acts 8, so that God should show he was accepting the Gentiles in Acts 10, and so that God could show that he was accepting disciples of John the Baptist in Acts 19. That wasn't his exact wording, but it was something along those lines.
The Acts 19 explanation smelled of poppycock. Jesus had disciples who had been disciples of John the Baptist and John acknowledging Jesus was part of the message the apostles recounted as seen in the gospels. So it seems rather silly to think that they would need some special supernatural acknowledgement. Paul was already ministering among the Gentiles at this time.
Come up with some kind of special reason why something in scripture happened as an excuse to rule out that scripture being 'profitable for doctrine' in other ways is a poor approach to scripture, especially if the reason one argues for is unrevealed-- the Bible doesn't teach it.
I'll give another example. Some believers-- especially those influenced by Reformed thinking-- may argue that the reason Jesus did miracles was to demonstrate His deity. I am not necessarily disagreeing with that, though I do think it is more nuanced than that, because the Man Christ Jesus was also doing miracles by the power of the Spirit. I seem to recall John Calvin making the point about Christ doing miracles that proved His divinity in at least one commentary on a passage, that I don't remember the specifics.
The problem comes when someone argues that the exclusive reason for all of His miracles was to prove His divinity. Then you run into problems with actual specifics of passages. Jesus fed the 5,000. Was the only reason to prove His divinity? Doesn't one of the passages point out how Jesus had compassion on the multitude, who were like a sheep without a shepherd? Couldn't compassion be a reason behind the miracle. Is there nothing in the event to show that He was a Prophet? Elisha the prophet performed a miracle, through prophecy, of multiplying food? Is there no lesson there about trusting God for our material possession? What about Jesus using His servants to cooperate with Him in His work? He had the disciples have the people sit down and distribute the food.
You can come up with ONE reason and argue that this is THE reason something in the Bible happened. Even if you can find scripture that gives a reason something happened, that doesn't prove it is the only reason. And if you just make up the reason and it isn't taught in scripture, you could be way too far out on a limb.