Not only is it measurable, Facebook measured it. Years back, they did A/B testing to see if they could make users happy or sad. Turns out they could. They pub

Not only is it measurable, Facebook measured it. Years back, they did A/B testing to see if they could make users happy or sad. Turns out they could. They published a blog post about it. All subsequent mental harm their platforms do is squarely on them. They know. They admitted it. They should be sued out of existence.