The tricky thing is it doesn’t just add sweetness. Due to the sugar molecules being distributed densely in the water molecules, it provides a sensation called “mouth feel”, which refers to the denseness and viscosity it contributes to cocktails.
I think the keto diet's promotion of erythritol is one of its primary successes. Erythritol tastes like sugar to most people and is 70% as sweet as table sugar with almost no calories.