Thomas,
Let's be careful with the wording here. I think that saying "is the responsibility of the ICANN board" overstates the degree of influence ICANN actually has.
Thanks for catching my inaccuracy. I did not mean at all that ICANN was making the policy, but that it is rather the Board, not IANA, who has to approve the policy done by the RIRs. I thought, though, that the later sentence was explaining better (see below). I agree that the best way to influence the policy is to go where the policy is made (the RIRs) rather than where it undergoes formal approval (the Board). This is, IMHO, not very different than to say that to influence a GNSO PGP you go to the GNSO WGs.
is the responsibility of the ICANN Board. IANA deals with the practical implementation of the policy, but does not decide the policy. The policy is decided by RIRs/NRO, and has to be approved by the ICANN Board.
Cheers, Roberto