Your friend claims are true , the bottom branches are smaller and thin , they are producing what we are calling popcorn buds aka inconsistent buds , fluffy, aerated. If you cut the branch before the Flowering then the plant will redirect the energy to the upper parts .
He told you to remove the fan leaves because they are blocking light to lower branches/ buds sites , this method is called defoliation and it is helping to promote secondaries growth by bringing more light , the rules are simple : cut the leaves that are blocking light and keep the others, don’t remove too much leaves aka don’t strip her down.
Your friend is in right, google search for defoliation