Yes, but you have to pay for a line you don't plan to use much, so its capital costs should be attributed to the generation method requiring it. Which is fine, but not including it is dishonest about the true costs.

I think if you designed and built it with the idea in mind that you're building your renewables in the sunny/windy centre/south of the US to be transported to a these places all year round it's a better idea than it being a backup. But I agree that the cost of over generation should be factored in to comparison pricing. But I also think we don't include enough of the costs in FF infra either.

The coal plant in my hometown was always running on cold days. It didn't need anything else to be available when needed besides several hours of lead time.

Mostly relying on long-distance transmission has high costs in capex, opex (losses), reliability, and security.