The WHO has some valid points.
Nothing that people can put in their mouths that doesn’t reduce hunger can stop them from continuing to eat, so it can’t reduce weight. Artificial sweeteners by their names aren’t compounds that humans evolved to need or use.
But they also unnecessarily misused relative statistics as a justification.
“Results of the review also suggest that there may be potential undesirable effects from long-term use of NSS, such as an increased risk of type 2 diabetes, cardiovascular diseases, and mortality in adults”.
They increased risk by how much and to whom?
The health risks described are determined by correlations, not proven causation. They are small percentage correlations which are not explicitly stated. That distorts and uses statistics as an irrational scare tactic.
There’s an increased risk of collisions within 5 miles of your home. Should you park 6 miles away from your home and walk there?
There is a 100% correlation between the number of years that a person goes to a doctor and mortality. Should the WHO should suggest not seeing doctors to avoid the undesirable effect of death?
There are times to consider correlations of behavior with desired outcomes and use them when there is a lower correlation with an undesired outcome. But to do so rationally you need actual numbers, understand where they came from and what they objectively mean.
Otherwise you get things like statins being used for primary prevention, because they “reduce heart attacks by 25%”. It never reached 25% absolute incidence for any studied cohort. The total cohort reduction was from ~5% incidence to ~4%, a ~1% absolute reduction. The total of the reported “rare” adverse reactions (above placebo side effects) for the most widely prescribed statin is ~4% (Lipitor insert and FAERS) reports.) Although few of the reactions were identified as fatal, they reduced QOL for nearly the same number of people - a different group that those who had heart attacks- as those who had heart attacks. The most frequent adverse reaction reported to the FDA (16.02%) was - new incidence type 2 diabetes.
That’s not to say that statins might not be helpful for people with clinical evidence of hearty disease, but that the statistics were misapplied to establish statins for preventative care without established benefit for +80% of those people taking the drugs, and negative effects for 4% of them.