I'd like to see a source on that, because (excessive) sugar literally causes diabetes.

And of course high sweetener consumption is must be strongly linked with in general high calorie input and overweight people trying to reduce calorie consumption.

Your first point probably isn't actually true. The research that first connected the two showed that across a population sugar consumption up -> diabetes rates up. But it turns out that when you control for weight the effect of sugar specifically is much much smaller. To the point where if you're a healthy weight your sweet tooth isn't moving the needle.

Oh that's not true at all. First I think they taste better, they're sweet without being syrup-y. Second it allows me to drink a lot of soda, 5+ cans a day adds up when it has calories. I have no expectation that it helps me lose weight, it's just tastier water.

5+ cans of soda a day seems unhealthy even if it's not caloric, the gas and acid will mess up your stomach.

It is not just tastier water.

Given that in France "water" means carbonated water and you have to specifically ask for "still water" I can't imagine the gas being that bad for you.

Acid I can get behind but soda is by far the least acidic thing I consume on the daily.

The carbonation creates carbonic acid in your teeth. It’s a huge driver of calories.

Of the of the issues with diet soda in particular is your tastes favor sweets. I used to drink 4-8 cans of Diet Dr Pepper daily. When I stopped, after a couple of weeks I found my taste preferences to be very different. I’d favor savory more attractive and sweet stuff would seem too sweet.

I can't fine anything talking about carbonic acid and calories. Is there something you're referring to?

Maybe they meant cavities?

Probably typed “caries” and got autocorrected

Sorry - it was supposed to be “cavities”. Too late to edit I’m afraid.

No, they have not. The evidence points the opposite way (people lose more weight on non-nutritive sweeteners than sugar).