Is it okay to drop "through" here? or is it better to keep it to make this sentence more natural?
"Through" is important in this sentence and is needed to make the sentence sound more natural. In this sentence, "through" is a function word that describes what helps a restaurant business thrive: building loyalty helps a restaurant's business. Here are sentences where "through" is needed. Ex: We built a relationship through trust and understanding. Ex: He went through the tunnel. Ex: She had to go through many obstacles to win custody of the child.