"An interesting problem of labor is that humans aren't truly replaceable except in a system that has turned labor activities into essentially mechanical work..."
I'll distill the Coming Labor Apocalypse metaphor to its absolute essentials:
People do labor in exchange for food.
As hunter gathers, that meant hunting and gathering to eat. Let's ignore people gaming the system, parasites, cheaters, etc., for a moment. In modern terms, we "work" as an end to a means of "eating." Automation and misapplied AI disrupts this in the name of efficiency by interrupting the means for people to do labor that will allow them in the end to eat.
Of course, that means those elements of society that benefit in selfish ways from efficiency, let's call them people who game the system, parasites, and cheaters, end up with nobody able to eat because people no longer can provide labor in exchange for food.
In other words, if you have no money, you can't buy things. You can't eat. You become angry.
Efficiencies should provide more for everyone, but the short-sighted and selfish miss this.
Eliminating labor, without fixing the system (providing basic income, for example), leads to pitchforks and torches, thus the #ComingLaborApocalypse.