While it's true that just deleting an app doesn't get rid of its preference files and Application Support files (should it install any), most of them don't really matter. It's not as in Windows, where you have this one giant registry that gets messed up. It's simply files that clutter your Preferences folder a bit. AppZapper, in my opinion, is only for those who install and de-install, say, 10 apps per day. I find myself trying one or the other app a week, and I only clean up my Preferences folder every half year or so. No problems. Those preference files ain't big, anyway. At the beginning, AppZapper had its fair share of problems as well. Didn't find all related files, deleted some that _weren't_ related... I don't trust such a tool much. And in my opinion, there just isn't sooooo much benefit for me personally. Things like Garage Band's loops folder are an exception, of course. But I find things like that using OmniDiskSweeper. That's for finding large folders on your volumes.