I too had that same question in the past, and the answers I got for variables were that by using them directly was harder if in the future you wanted to change

I too had that same question in the past, and the answers I got for variables were that by using them directly was harder if in the future you wanted to change the "how things are stored" in the class. With nowadays ides it's as easy as a refactor, so not a problem I personally ever had. For personal projects I do use public things where necessary, and for team programming I also use public functions, but not public variables (sonar doesn't allow it) unless you make them final, which I do. The important part is "when necessary". Think that each class is like a small little library (it should be at least). There are things you want others to know and use, and other internal things you don't. Public for the first, private for the second.