If Google, Facebook, Twitter, Oracle, and Amazon are academics, then yes. If not, then free software is some of the best software you could ever use.

Please expand on the scenario about A,B, C,D, is this about ethics about A paying for D?

Yes. And everyone else, too.

Empower individuals and communities to create their own money. All money in Ripple is explicitly represented as debt, with transactions simply consisting of balances being shifted on a series of imaginary credit lines from the payer to the receiver. In order to explain how this works in practice, consider a simple example. Suppose there are two friends, B and C, taking a road trip, and they both decided to bring along a friend of their own; B brought his friend A and C brought his friend D. A knows B, but has never met C and D before and they may well never meet again, and similarly D has never met A and B. Now, suppose that A and D are out getting a coffee, but D does not have money to pay.

Isn't freedom for academics?

Yes, and everyone else.