Let me ask this. How is Flattr accepting payments on people’s behalf any different than when Readability does it?
Is it that if you try to send someone a donation through Flattr and they don’t use it you get a shrug back going “Uh, sorry – this person doesn’t use Flattr and you’re going to need to find another way to support them.”?
To compare, Readability goes “we’ll take your money anyway and put it into this pile.”
I honestly don’t know, although from their homepage it looks like it only works with Flattr users.