For those who are unfamiliar, the Reclaimer building produces iron, coal, gold, nickel, aluminium, oil, and uranium from buildings which require those resources (or create them, like uranium mines) based on the amount of pollution on the Reclaimer building. There are three intertwined problems which make the Reclaimer busted.

1) The reclaimer does not reduce pollution seemingly at all. If it does, the effect is so slight as to be meaningless. This means it does not reduce its own efficiency.

2) Industry buildings create pollution even when they're not actually making anything. This means (for example) you can slap a steel mill next to a reclaimer and with no previous resource extraction (mines), you can create magic steel out of air.

3) The amount of resources produced by the reclaimer outstrips raw resource production from actual raw resource buildings, and unlike mines, the reclaimer never runs out of pollution and does not have employees.

Edit:
You can actually turn the industry buildings off, and the reclaimer produces the corresponding resource anyway, provided it never runs out of the resource in question. You can therefore create a maximally efficient reclaimer with one each of the below:
Tannery (Pollution)
Steel Mill
Jeweler
Battery Factory
Plastic plant.

Costs one employee to run the tannery and the filter replacement/electricity costs. The actual production plants can be mothballed. Ergo "3. these setups really only work when you have not just workers but workers AT work" turns out to be wrong.