There are many ways to do this.
But at the end of the day, the question that always comes up is "Why do you want to?".
Remember Tableau is a Data Visualization tool, and not Excel, or an ETL tool. Though we can make it produce Tables that look like Excel, or we can manipulate data similar to ETL Tools, we shouldn't confuse what Tableau with those tools. Tableau is the best Data Visualization tool on the market. Emphasis on Visualization.
Instead of hacking Tableau to make an Excel Table, what are other ways you could visualize your Data to give deeper meaning and understanding to your users?
Sorry, I don't mean lecture, but this question comes up a lot, and the responses are usually along these lines.