If you want to treat your windows instance as a scratchpad, installing and uninstalling software multiple times, then do not be surprised if you get unexpected side effects.
If you want to know how SQL Server 2012 will behave on a clean instance of Windows, then always install it on a clean instance of windows. If you want to find if you can get SQL Server to appear to install OK on a server that has had many installs and uninstalls and which may not work in exactly the same was as on a clean install, carry on as you are.
Original author: https://github.com/SQL-FineBuild/Common/wiki/ 1-click install and best practice configuration of SQL Server 2019, 2017 2016, 2014, 2012, 2008 R2, 2008 and 2005.
When I give food to the poor they call me a saint. When I ask why they are poor they call me a communist - Archbishop Hélder Câmara