you've never had to only have 1 class per file. You can only have 1 public class per file however. You can also nest classes in other classes for quick little

you've never had to only have 1 class per file. You can only have 1 public class per file however. You can also nest classes in other classes for quick little data types you need locally. So the notion that every single last tiny class has it's own file hasn't ever been true (even if thats the coding style in a lot of code).