Physically, you are talking about signals measured in the tens of nano-volts (or nano-amps, depending on the mechanism of the microphone).
Also, it's less about the absolute resolution, and more about the ability to boost the gain, often by a lot, while still having a wide and useful dynamic range after the fact.
The stacked ADC approach does allow for a wider overall dynamic range, but I would be skeptical of the physical transducers capabilities in using it all, but the 32-but float format here appears to be largely about lossless transfer to a DAW such that further processing is lossless, as we are not converting from int to float and back.
This format could then be said to be useful as a master media format.
The article in the OP is about a flac containing a 32-bit int audio stream, however, which appears less useful and not at all related to 32-bit float