Windows 3.0 didn't have any standard system dialogs, these were introduced in 3.1, but that is not the main point. In Windows 3.1 the directory selection dialog was exactly the same as file open/save dialog (Figure 8 in the article) but didn't let you to choose files (and there are still places in windows where standard open dialog is used for choosing directory).

What is typically used as "standard directory selection dialog" actually isn't even documented standard WinAPI dialog, but originally internal dialog of the explorer shell (and it would not surprise me it it was not present in original Windows 95 RTM but introduced in some slightly later version), also it does not select directories (ie. pathname as string), but shell folders (ie. ITEMIDLIST).