TL;DR: Correlations does not imply causation.
Having said that, if you can find a negative correlation AND there is a strong reason to believe that the negative correlation will hold as long as X and Y hold, then the tool could be very useful.
Having said that, if you can find a negative correlation AND there is a strong reason to believe that the negative correlation will hold as long as X and Y hold, then the tool could be very useful.
The correlation is only a first indicator.
The TLDR is more that correlations throw a lot of information away.