I would like to ask if there is some particular reason why was the knife tool used for making those dents? It seems to me that using loop cuts would result in a faster workflow and better topology?
You can certainly use loop cuts instead of the knife tool. Only drawback with loop cuts for isolated details like dents is that it generates more polygons than is necessary to achieve the shape. In this example below, using the knife cut results in 9 polygons where the loopcut in your example generates 12:
9 vs 12 isn't a huge deal but multiply that by 10s or 100's of isolated details and it can add up. Which only really matters if you're building a game-ready model. Technically this project is "lo-poly" instead of "game-ready" so it doesn't matter that much.