If there were no weighted grades, you'd know that if you had a 4.0, you would be valedictorian (but you'd still share it with everyone else who got a 4.0). Weighted grades create an amorphous system. You don't know how much you need to come in first. Pursuing the actual number one spot in a weighted GPA system has to cause a lot of stress and uncertainty, but it seems like a good idea to keep the easy-A strategy from working too well.
Just to be a bit of a devil's advocate, so what if there are 41 valedictorians? In my own high school, I watched the competition of valedictorian versus salutatorian between one of my best friends, and a girl I was dating off and on, come down to the last hundredth of a point --- and be resolved when the girl secretly enrolled in a summer course in tennis. (Secretly, because the other could have enrolled in something with a higher weighting at the last second, had the plan been revealed.) The A on a summer rec course made the difference --- both of them had had 4.0 since roughly first grade.
(Now, 30 years later, the salutitorian has had a respectable, undistinguished career and a couple of kids; the valedictorian made it to doctoral comps, didn't pass comps, and had a breakdown. The extra 0.01 points did lots of good.)
Eliminating grade inflation is a fine idea, especially (I sometimes teach undergrads, believe me when I say especially) when I see what the education system is teaching. But is competetive placement the goal? Or would we be better off to be trying to make sure that every student is mastering every topic first?