Recreational drug kratom hits the same brain receptors as strong opioids

Totally agree. The headline could easily have been ‘Recreational drug kratom is in fact a weak opioid’. The original headline’s use of the word ‘strong’ is superfluous. Either it targets the same receptors or it doesn’t (or only some of them, or additional others, etc). All other things being equal, binding affinity and agonist type (partial, full, super) are the main factors determining ‘strength’.