Correct, it puts beneficial bacteria in your tank called aerobic, and anaerobic microbes, as well as natural enzymes, and to enhance the rate of nitrification, denitrification, and organic waste degradation.
Benefits are.
1. Rapid redution of organic carbon, ammonia, nitrite, nitrate, and phosphates.
2. Digestion of uneaten, and undigested food, excreta, detritus, and other stuff. (so you don't have to stir substrate).
3. Reduction of organic compounds into nutrients that encourage the growth of photosynthetic organisms, like zooxanthellae , macroalgae, and plants.
4. Greatly reduces hydrogen sulfide production.
5. Increase in dissolved oxygen concentration.
6. Limits availability of pre-existing phosphates to undesirable forms of algae, and cyanobacteria.
7. Increased water clarity.
That's why the skimmer skims better, (not crazy, but more)