Earlier quoted context omitted.
> it screws up the class curve This is your problem right here. There is no rational argument for grading people on a class curve. That just makes the class a lottery and incentivises sabotaging for others to get an upper hand yourself.
Of course there’s a rational argument to using the distribution of scores to set the grades: If everyone in the class gets half the questions wrong on the final exam, you shouldn’t just fail the whole class! The test was probably just harder than expected But in that same example, if many of the students get close to 100% on the final by cheating, then the remainder of the class will suffer
That way you don't incur any of the (pretty severe) drawbacks of a curve but don't punish students for questions that were badly phrased or weren't properly taught.