The reviews are fake, the no-name brands are hallucinations, and no one should ever buy supplements, food, or safety equipment like climbing rope or fuses from a disreputable platform that sells electrocution hazard USB chargers and does nothing about them. Watch a video or 3 from Louis Rossmann and BigClive.
I buy all my supplements on Amazon. I buy paracord and carabiniers on amazon, I've hung more than my body weight from them no problem.
Carabiners break when they break. You'll only notice if you get unlucky. I think there's carabiners you wouldn't want to use that can hang weight "no problem" for a while.
Problems with supplements are even more undetectable.
The biggest issue with reviews in the UK are the Vine reviews, and occasionally sellers aggregating reviews for unrelated products. Fake products seem to be almost nonexistent (maybe because of stronger market regulation?).
Same/next day delivery is hard to compete with anyway.