This is true because:
The income of partnerships and LLCs (taxed as partnerships) is taxed directly to the partners and the LLC members. By contrast, a C corporation pays tax on its income and then the shareholders must pay tax again on the after-tax profits distributed by the corporation resulting in higher overall taxes.
While S corporations, unlike C corporations, are not taxable on their income, partnerships are still superior to S corporations because of the greater ability to deduct