It is not to completely deny the existence of dumbbells, because the position of holding the resistance band will affect the resistance, and the different holding positions will make the resistance of each training different. In addition, the resistance bands rely on elasticity to provide resistance, but the resistance is very small at the beginning of stretching, and when the resistance bands are relaxed, no force is required at all. Therefore, it is necessary to stretch the resistance band to a certain length. After pulling, other muscle groups need to cooperate to exert force. However, the target muscle group has not yet exerted force, and the synergistic muscle group will exert greater force.
So resistance bands and dumbbells can complement each other. And throughout the movement, due to the different resistance, after the peak contraction, the feeling of the eccentric contraction process will become weaker and weaker. Even if you have gathered your "vigor and energy", the distance you can "struggle" is shortened. Dumbbells may work better in this regard. So all in all, the actual decision on which tool to use depends on the requirements for training effects. The two tools cannot replace each other, they can only complement each other.