No doubt, it is not unique. I guess if one believes the Astros are dumping their players so they can lose and reap the benefits of more draft money, then this appears unique. In this scenario, the uniqueness would be a result of the new talent acquisition rules, which weren't in play for the Nats or the Rays and all the other rebuilding teams.
I just don't believe the gain from such a strategy, a few million more in talent acquisition money, is going to be that significant over the long haul, and would therefore never justify the negative effects of a tanking strategy. I don't think Luhnow or Crane believes this either, they are just trying to quickly retire the debt.