Not the case universally. My son's school in south-central UK does everything via Google Docs or apps specially built for distance learning. If it weren't for Minecraft mods, he'd have no concept of the file system.
Well, in Google Docs you have something that looks a lot like a hierarchical filesystem (whether someone actually creates folders or not). The fact that it's not actually a filesystem as traditionally understood is sort of irrelevant. The average filesystem user didn't know about inodes, journaling, etc. either.