What measurements do you propose?
There's the aphorism that what's measured gets improved (and what isn't measured gets worse). If you're trying to improve diversity/inclusion, how do you know you've done a good job unless you can measure it?
So, for example, if Silicon Valley is 10% African Americans (I have no idea if that # if true, just using it for argument's sake), then your organization should be 10% African American. This also means your organization should be 50% women, since they are ~50% of the population. How you manage that (blind hiring, quota hiring, etc) is up to the company, and is difficult. But measuring proper diversity is really easy: you should reflect the local city's diversity. If you don't, you need to have a really good reason (and "we don't think we can be drinking buddies with them" is a really shitty reason).
If you pick a "zero" tolerance, that's saying your measurement can actually be zero and there's no need to improve from that point. If you pick a measurement that can only asymptotically approach zero, then you are recognizing that improvement is always possible.
If you're not half-assing your zero tolerance policy, measuring it is immaterial. Find an offender, fire them. The number of firings in hindsight isn't a factor towards your future, since those people are gone. There's not a meaningful measurement that you can make, because after you fire someone, they don't impact your numbers anymore. You assume the problem is ongoing and will continue to be ongoing, you immediately and harshly deal with the problem when you encounter it, and you move on to finding more problems. There is no gray area.
They would if your measurement is incidences per month. Otherwise you could fire someone every day and think you're doing a good job at office culture. I'd rather not have any harassment. Of course, you'd need to be careful not to discourage reporting of incidences. Measuring things is tricky.
> Find an offender, fire them
What's your technique of "finding" problems? Could it be improved? How would you know?
> no gray area
Of course there is. How do you know when someone accidentally insinuated sex versus intended a salacious proposal? Or accidentally touched someone's rear while passing by? Because it happened 6 times in 2 days? What about 2 times in 6 months?