Using the QCD you avoid paying taxes on that amount even if you use the standard deduction and your AGI is reduced which might lower your tax on social security and other related taxes. Of course the trade off is that you don’t have that amount to spend.
@Tigeramoma the benefit of the QCD begins with whether you are in the state of mind to donate in the first place. If you are going to donate anyway, this is a great approach. if you are not going to donate, then you'd really have to think through why you are doing this.
Let's say you would like to donate $10,000 and you are over 72 years old (required to take RMDs) and take the standard deduction
Under either scenario, a $10,000 distribution meets part of your RMD requirement.
a) you could take a $10,000 distribution from your TRAD IRA and then donate the money. You are taxed on the $10,000 and pay the appropriate tax. You can't use the donation to itemize because your deductions are less than the standard deduction. Alternatively, The charity gets less than $10,000 because you hold back some of the money so you can pay the tax. The point is there is tax to pay on the required distribution and either it comes out of your pocket or you donate less to the charity.
b) you do a QCD for $10,000. This is the best of both worlds. The charity gets the entire $10,000. You pay NO tax on the distribution. This is the elegant approach if you were going to donate the money anyway.