This myth was busted long ago. Eric Borneman showed pictures of two tanks tied to the same pump with higher phosphate. One tank had a mass amount of algae the other fine. What was the difference? Herbivorous.
The only issue with this is there are different type of algae. You need multiple type of herbivorous because they eat different things. Different tangs eat different algae and allot of people do not have large enough tank to have multiple tangs and not allot of people want to risk angels.
The other issue with high phosphates is you got to be careful you do not introduce a algae that these herbivores do not eat. Happened to may friend who had multiple tangs and other herbivores. He introduced a frag with dictyota on it and overnight it took over his tank and pushed him out of the hobby. I introduced the same algae since we split the colony and it did not spread in my tank. Actually pushed him out of the hobby it was so bad. Never seen anything like it.