I don't really have a problem with that, or people busking online. But before you plug in those credit card digits, you should ask yourself: "If I met this person on the street and they asked me to fund their {pet's surgery, vacation, novel}, would I do it?"
I had my "a-ha" moment for crowdfunding about 8 years ago. A friend-of-a-friend who was a promoter/bartender, whom I had just met, asked me to fund his Jewish contemporary art show. He seemed very passionate about getting it going. The total sum required was a few thousand dollars, so it seemed like an honest pitch. He friended me on Facebook and sent me the link to Kickstater. Later that night I was about to make a donation, but I stopped. "I don't even know his guy. Why am I giving him $50?" And that's when I linked the two behaviors.
Just because there's a nicely designed UI between you and the beggar doesn't make it something other than begging. I call it "busking" as opposed to "begging" because they are actually performing - they're (both the website and the person; they work in tandem) trying to make you believe they're not a beggar.