I think it's important to note that this was strictly an observational study that they explicitly describe as "conditional". They don't go into the how or why of it. It could be that it's a negligible change or that participants overindulge elsewhere because they cut it out of sweeteners or that the most at-risk use sugar alternatives or that they lose weight in the short term (mentioned in the article) before reaching their new maintained weight.

Honestly, I think the last part is very likely, or a mix of many of those. They say it doesn't have a long-term effect, although it can have a short-term effect. So if you decrease your calorie intake a little, you'll lose weight until your calorie output matches (less weight mean less effort to move).

So, it's not an end-all solution.