TV and radio stations have been using compressors for years and years to actually ADD the loudness to start with.

Think about it, adjust a compressor a certain way, and it will make the quiet bits loud and the loud bits quiet, to "average" the output.
So the peak volume of the ads is no more than the tv show, but the average volume is much higher.
And it is the average volume that our ears notice more than peak volume.

This "compressor" that ACA is talking about is merely adding another level of audio compression to the ads to quieten the average output, the only problem is it doesn't know when it is an ad or a show, so it will also average the output on the show, ruining the intentional gain adjustments in the soundtrack.