Note that as I understand the main claim of Marx is that the efficiency and productivity gains from automation don't actually go to the laborer, they're captured by the "capital owner". Example being how despite all the automation we're all still working 8 hr days, 5 days a week just to get by.

Now of course there's also jevon's "paradox" here, and the automation does allow us to support a larger population so in that sense not all the increased productivity is just "skimmed off the top" as profit. But on the flipside the crux of the other recent [1] HN post is that the wealth disparity is increasing. And if all the increased productivity directly translated to more "physical resources" in the world, that wouldn't be the case.

So something must be getting skimmed of the top, and intuitively you can feel the "rent seeking" layers in society have increased. Gains in efficiency are no longer resulting in surplus of physical products and decrease in prices.

[1] https://news.ycombinator.com/item?id=48038307