Increasing Returns

Fixed costs & market power in tech are a fact of life. But this need not correspond to simple IRS b/o duplication & business/idea stealing

I don't know what "essential" means. And ideas are rival in a market economy with a patent system.

Spoiler alert: Anti-science is especially dumb

Yes, if you mean that Af(x) has increasing returns in A and x. Not restricted to market economies. Generation, copy of ideas is important.

An idea is non-rival and having one requires a large upfront cost (as in discovering the cure to a disease). Increasing returns follows.

This also means large potential gains to globalization.
-see background information here
-see background information here

One of the central insights of economics.

The increasing returns created by nonrival ideas is perhaps the leading contender for explaining economic growth.

True if we assume, as it seems natural, that doubling all rivalrous inputs doubles output.

The key point is that developing an idea is a fixed cost, not that ideas are nonrival. Conclusion also follows if ideas do not transfer.

This is the key source of improving material well-being over time; disruptive as it can be.