[gojomo]

That's interesting; I'll have to think about that. However, I'm not sure it holds except to the extent that the copying is slow and the buyers impatient. Then, the first batch captures enough of the market to incent the author.

But if most of the market is patient enough to await the arrival of slow-copycats, the initial investment in the 'first batch' (by not just the creator but the publisher/wholesaler/retailer is in danger, and thus deterred without copyright. In fact, large losses could be incurred being stuck with an inventory that's later undercut. Fears of such losses could cut off a gradual build to popularity before it starts.

Digital reproduction/dissemination eliminates the need for most of that 'first batch' investment and all the downside risk of production/inventory; only the creation itself must be incentivized. All the other once-necessary costs no longer need a legal hack (statutory monopoly) as a sort of subsidy.

I'll have to look at the Breyer reasoning to know what factors dominate under which assumptions.