The only benefit might be helping to oxygenate the water and a slight benefit to keeping pH stable. Overall, you would be much better to aggressively use activated carbon.
In saltwater, the organic impurities in your water will bond at any place where water and air meet. This bond creates a think gel-like substance, which is what collects in the collection cup of your protein skimmer. This bond does not take place in freshwater, so the protein skimmer will not actually "foam" and will not remove any impurities from the water.
If you think about walking down the beach, and the waves crashing on the shoreline, you will recall seeing a thick foam of bubbles which is carried up onto the shore. You will not experience this at even the largest of freshwater lakes.
"Looking in windows, knocking on doors, they need to take seven and they might take yours."