When I installed M2 CE with sample data I had a .htaccess and .php_cs file in the M2 root folder.
When I installed it without sample data the installer missed these two files (and maybe other hidden files?).
M2 wouldn't work at all without the root .htaccess file, so I copied one in from my original install. So, what about the .php_cs file? Is this required? Site seems okay so far, but just wondered.
The .php_cs file is used only for the GitHub pre-commit static reviews: https://mage2.pro/t/506
You need not it.