second stage fermentation

Hi All, Looking to brew my first all grain beer using fruit. As part of the recipe I need add fruit to the beer in secondary fermentation. What's the benefit of transferring to a separate secondary fermenter vs. just adding in the fruit into the primary once primary fermentation is complete...

Cherry Apple Mead siphoned from primary to secondary fermenting bottle for the next two to three weeks, depending on how it looks. Will post a picture of the final result