Free weights = constant resistance. Bands = ascending (harder as they stretch). Research from the Journal of Strength and Conditioning: bands produce comparable muscle activation for many exercises, but patterns differ. Bands maximize tension at full extension; weights maximize it at the stretched position.
Real Answer
Bands don't replace heavy compound lifts. They're superior for rehab, travel, accessory work, and combining with barbells for accommodating resistance.
Can resistance bands build muscle as effectively as free weights?
For beginners, bands can produce similar gains. For intermediate+ lifters, free weights are superior due to consistent loading and progressive overload capability.