One brings this up in the light of the recent study by Avecto which found that the harm caused by malicious code on Windows systems could be largely mitigated by operating as an ordinary user.
Avecto found that 94% of 530 vulnerabilities listed by Microsoft itself could be mitigated by removing admin rights.
One answer as to why Microsoft does not insist on creation of a user account in order to use Windows is the fact that for many long-time users, the ability to do everything from one account has become a habit. Security and convenience are enemies.
And when about 92% of the world's desktop users are running one version of Windows or the other, that's a lot of complaints.
But these days, given that one can authenticate as administrator from within a user account when needed, perhaps Microsoft should have given some thought to at least making an user account compulsory on Windows 10.
Apple's macOS and the older OS X are grounded in UNIX and use the sudo system where the user has to authenticate every time an administrative function needs to be performed.
On a Linux system, one cannot start using the system unless one creates an user account. Assuming administrative rights is simple; more hard-core users do it from the command line but most other applications bring up a dialog box when admin rights are needed to do something.
The danger of running any computer, no matter the operating system, as an administrator is that any file created or downloaded has the same rights on the system as the user who downloaded or created it. And it is very easy to hose an entire system.
If Microsoft did decide to bring in compulsory user account creation, that would affect companies that sell anti-virus and anti-malware products. This is a multi-billion-dollar industry that lives almost exclusively off Windows.
Avecto's findings should make people sit up and take notice. Along with using an ordinary user account, there are several finely-grained settings on a Windows system that make it so much safer to use.
Perhaps Microsoft should launch some kind of education campaign in this direction.