In general people want products that will enrich their lives in some way. Sometimes these things aren't necessities, but sometimes they are. Food for example...

I introduce a new food product, Soylent Green. It tastes great, doesn't cost much and is nutritious. It starts becoming wildly popular.

Does that mean that there was huge demand for cannibalistic products? No. There was demand for tasty, cheap, nutritious food.

If this happened in real life the ingredients label would be a list of indecipherable chemicals, proteins, and "natural flavors". What you're suggesting requires that consumers be able to understand the externalities involved in the sourcing of every ingredient as well as the manufacturing process AND then use those to override their own preferences regarding the end product.

Identifying and preventing externalities or at least making sure externalities are factored into pricing is something that governments are MUCH better equipped for than any individual.

If you can sell a product at $5 by doing it in an unsustainable way but can't afford to go below $10 if you do it in a sustainable way, is it reasonable to expect each individual consumer to fully vet claims of sustainability and make the right long-term decision?

This is what you're pushing for, and what we have, and it's a terrible world to live in since it lets you the producer who is knowingly doing damage to avoid taking any responsibility and just push it all to "consumers."

Whatever happened to personal responsibility applying to rapacious producers too?

Consumers didn't hold a gun to anyone's head and force them to profit from environmentally disastrous manufacturing and shipping practices, or to profit from literal slave labor in supply chains. Those actually committing those actions, and profiting from them, are responsible for their actions, and it's shifting the blame to suggest that those who have no say in how private businesses are run are responsible for how private businesses are run.