to spend otherwise taxable income on whatever they deem important

Yes, that's absolutely true, but the language hides the truth a bit. People don't get the nuance of what "taxable income" is.

If Bill donates a thousand dollars to charity, he saves ~$370 in taxes. That means he's still losing $630 on the deal. The government gets to effectively triple their money by allowing you to decide where it goes.

There may also be a limit of 60% of your AGI? I'm not sure how this works with billionaires.