It is not accurate to say that resistance bands are better or greater than free weights. Resistance bands are ideal for beginners or someone who has no access to the gym.

Resistance band and free weights both have different roles to play depending upon individual's goals or situations.
The choice of whether you’re going for weights or resistance bands is highly subjective.

Resistance weight stays the same during the full range of motion.
If building muscular strength and power is your ultimate goal, free weights are an absolute must. Resistance bands won’t be able to challenge you in the way heavy, consistent weight will. As you start to get stronger, there is a finite level of how heavy of a resistance you can achieve with a band alone. Progressively loading even the heaviest band will just result in it breaking, which is not a marker of your strength, simply the band’s breaking point. Once you’re comfortable performing exercises correctly with bands, trade it for a comparable weight with free weights to boost your strength.