How obnoxious. I would hate that too, and would be tempted to refuse. Is that a common thing to do these days? With the seriousness of academic dishonesty charges, I don't see why students would put up with this.
If someone wants to bring meritless flimsy accusations, I wouldn't want to help them do their homework in running down all the accidental matches found by their commercial provider, let alone rewrite my work in the process.
They aren't accusations just match scores. The scores are pretty meaningless unless there's a really good match. Obviously one shouldn't use that alone to determine guilt. Charges are decided by professors and committees, not turnitin. Yes some students might be concerned about the partial matches to the point of anxiety, but the solution is to simply assuage those fears. Because unfortunately, too many others habitually cheat with a misguided confidence that they can get away with it. Not to mention a completely warped sense of the risk versus reward for what they are doing. Making them go through turnitin is a way to dissuade doing that. Letting them see the scores before they submit the assignment is also a nicer way to push back. As opposed to having to hand out F's to get the point across.
The parent commenter's experience suggests that teachers are not doing that; instead, they're encouraging people to rewrite non-plagiarised work so that it doesn't trigger partial matches.
That is my experience too: teachers don't want the hassle of figuring out what a false positive really means.
If someone wants to bring meritless flimsy accusations, I wouldn't want to help them do their homework in running down all the accidental matches found by their commercial provider, let alone rewrite my work in the process.