First is the idea that a rich person can measure the "best" type of poor person. Excluding criminals, there aren't better or worse poor people. Just people struggling to survive.
The second is the idea that charity isn't beneficial. I've personally benefitted from countless acts of small charity throughout my life, and I'm not even poor. Nowadays I try to pay it forward by donating to Watsi, and I'm quite certain that the kid whose finger got cut off by a bandsaw is now grateful to be treating his staph infection, thanks to charitable donations.
The third reason is that it's being used as a talking point on HN rather than us, y'know, thanking her for giving away so much when she didn't need to. It's implicitly criticizing what she's doing. Which would be fine, if the critique had merit. But what is being proposed here, exactly? A wealth redistribution program that makes such "donations" mandatory?