Landfills are not a miracle technology. They exist already and are technologically sound. It’d be way more of a miracle if we somehow managed to greatly reduce waste.

People love to "what if" landfills. Best to not bother arguing with them. We have tons of problems with emissions, plastics pollution, industrial dumping. However landfills ain't one of them, but people won't give up. I've learned to not bother discussing anything with them if they don't know a few basics of how modern landfills are run (at least in western nations).

As others have mentioned they are a major source of methane emission, though this can be addressed (do a better job separating out food waste and compost it).

Landfills were demonized for a long time because they were easy targets.

It's usually just disguised NIMBY-ism :)

The thing about nimbyism in this case is that confortable commentators on hackernews are vanishingly unlikely ever to have to live near one. This is a poor people problem.

There’s a famous landfill right in Silicon Valley though; it’s caused Milpitas to smell like rotten eggs for the last 20 years.

https://sf.curbed.com/2019/3/19/18273029/milpitas-odor-studi...

Correct, landfills are not a miracle technology. Landfills leak.

https://www.clf.org/blog/all-landfills-leak-and-our-health-a...

https://pubs.usgs.gov/fs/fs-040-03/

How sustainable are landfills? There's limited land for farming, residences, manufacturing, and everything else we use it for. And trucking trash to deserts to landfill there isn't carbon neutral either. Trash also doesn't breakdown as quickly in covered landfills (for better or worse depending on what one dumps).

Given the yield of useful content vs. rock in mining, I suspect the more limiting factor is space for all the mining, not space for disposal of the 0.1% metal etc yield for making industrial goods.