While it's true that Dojutsu users tend to be extremely powerful, relying purely on Visual Prowess will not provide the biggest possible power. An example was the recent fight between Juubi Mode Madara and Maito Gai after he opened the Eighth Gate of Death: while Madara did defeat Gai (who was relying solely on his body's strength), he would not have survived without the regenerative powers of Hasirama's cells and the Juubi's chakra. Therefore I believe that you need both Visual and Body Prowess in order to reach maximum power.
Further examples: Ootsutsuki Hagoromo- used Senjutsu (stated by Madara in the latest chapter while observing Naruto's transformation)
Indra- only depended on his Visual Prowess, defeated by Ashura (stated by Hagoromo during his conversation with Naruto in his subconscious)
Uchiha Sasuke- awakened the Juubi's eye, thanks to Hashirama's cells (Kabuto stated that he was transferring Hashirama's cells to his body)
Nagato (Six Paths of Pain)- relied solely on his Visual Prowess, defeated by Senjutsu user Uzumaki Naruto