Here Peter Todd writes:
[A]s an optimization Bitcoin goes a step further and disallows invalid transactions to be published in the blockchain at all, but that's the thing: that's just an optimization that full-nodes don't actually need to operate.
Maybe I'm misunderstanding this, but it seems to be an interesting idea: the blockchain can contain invalid transactions, but all validating nodes will ignore them. I'm thinking, what if bitcoin was designed this way, or if someone created such hard fork, could it work? If yes, what drawbacks should be expected?
Correct me if I'm wrong, but probably Counterparty already works in this way, since they use bitcoin blockchain.