They are manufacturing their own from copying the original blocks. Thus this affects shape, clutch power, print quality, color tone consistency and sticker quality in a bad way. Also the raw plastic material itself injected into the molds has quality issues.
Their manuals are also shitty. Copied straight from the originals, but squeezing more steps on less paper. Colors are off, and 1:1 comparisons (needed for technic axles) are rendered useless.
You simply can't have the same quality of genuine Lego bricks at a lower price. This is not even counting in the intellectual property of the creations itself as well as licensing contracts for franchise related sets.