AutumnPirate Most apps create hidden files, for example registry entries and content in ProgramData or AppData. A regular uninstall sometimes removes some of this, but rarely all of it. Some of these files can prevent a game from working, for example the License folder is hidden, and a corrupt license file for a particular game can make the EA App think you don't own it.
Revo is one tool that looks for these files and deletes them too, and it's free and reliable and easy to use, which is why I suggest it when someone might need to do a clean uninstall of a game or the EA App. I've used it myself to remove Sims 3 and 4 a number of times, mostly for testing, and haven't found a problem yet. That doesn't mean it's always necessary, and you can of course try the normal uninstall process first, but if it doesn't work, it's time to try something more thorough.