I have been working in various technical support roles for many years and in addition I receive many requests for help with computers from others. What follows applies to many users but not all.
Users are not generally curious about their computers and they certainly are not interested in maintaining their computers properly. By which I mean ensuring that security updates are promptly applied, virus checkers updated regularly (or even installed), etc. Users just want a tool to do a job ... whether that be word processing, Internet access, games, or any of the other millions of things that computers can help with.
Despite improvments made over the years, every computer still needs a certain amount of system management to maintain it properly. And as can be seen by the millions of zombie computers owned by spammers, users don't perform that task.
What these users really need are systems maintained by others where all the boring system maintenance can be done by people who are paid to do that. There are a few systems like that ... Sun Ray terminals, Amstrad email terminals, etc. Unfortunately what those systems have in common is that they are extremely limited.
What is needed is something more like a conventional system based on Linux. The local hard disk would be a cache for filesystems stored on an ISP's server(s), software would be installed and updated by the ISP, and the users files would be backed up on central servers.