Why Do Charities Or Solicitors Send Return Address Labels? (A First World Inconvenience)

I've given just enough money to a small number of charities to be inundated with requests from seemingly everywhere and everyone. Each mailing, without fail, includes 1 or 2 sheets of return address labels. Why? As time goes on, I do more and more of my business online, so I need fewer and fewer return labels. In fact, it seems counterproductive to include links and/or QR codes to give online while also including these labels.

At this point, I have enough labels for the rest of my natural life AND the afterlife (assuming God will have some type of postal service). Rhetorical question: who advised all these charities that return address labels were the thing that would encourage people to donate? And if I may shake my fist and shout to the sky, can y'all just stop with this nonsense?

Okay; rant over. I yield the soapbox to the next speaker to air their equally inconsequential concern . . .