I don't think there's one particular tool that answers all questions. It would be nice though. Coming to your question, Tableau is designed to be able to visualize data, look at your data in a different perspective. It is not inherently a Data Analysis/Science tool. In Data Science process visualization step comes much later, to get there you need to first collect the data, clean it, transform it to a usable format. Then you build models/algorithms or perform Exploratory Data Analysis to find patterns, gain insights so basically you're turning your data into information. This is where programs like R, Python or SQL come into play. Finally, you'd turn this information into insights by visualizing it, so the end user can easily understand the results of your work and here's where tools like Tableau come into play.
In short to become a Data Analyst/Scientist, you'd not only need to understand a particular tool, but your data as well.
Here are some links,