Why ban it? At 2.7 transactions per second all a government would need to do would be to flood the one and only centralized Bitcoin blockchain with meaningless

Why ban it? At 2.7 transactions per second all a government would need to do would be to flood the one and only centralized Bitcoin blockchain with meaningless transactions. It's hard to pay for your child porn if you can't ever bid up your transaction high enough to be accepted into a mined block, and it wouldn't be expensive at all to accomplish this feat for even a small national government, let alone the U.S.