Being used for amplification attacks isn't bad if the amplification factor is low (ie. <5), and there is no way to chain amplifiers. You can also protect furth

Being used for amplification attacks isn't bad if the amplification factor is low (ie. <5), and there is no way to chain amplifiers. You can also protect further against it by limiting the amount of un-acked data per second to each AS. Well behaved connections generally will ack nearly all data sent to them, whereas attacks will ACK none. That way, users have to wait one extra roundtrip if an attack on them is in progress - doesn't sound so bad. Amplification was only a really bad problem when amplification factors over 100 were possible.