Resistance is resistance whether it comes in the form of weight plates, kettlebells, bands or a person’s own bodyweight. All will help strengthen your body. The magnitude of overload/resistance applied to the muscles and how the resistance is moved will determine the training effect derived (max strength, strength endurance, explosiveness, hypertrophy etc.)
Weights have their advantages and disadvantages, bodyweight calisthenics have their advantages and disadvantages, resistance bands have their advantages and disadvantages. Find a combination which works for you and run with it.