Windows wasn't unsafe to use, Internet Explorer and Outlook Express were unsafe to use. It had nothing to do with a lack of app stores, and more to do with the fact that ActiveX controls were allowed to run rampant on a machine, and that they could install themselves with a single dialog box that nobody ever paid attention to, and sometimes even bypass that.

I mean, even with an App Store, IE would have been pushed hard, just like Edge is now. And it still would have been a buggy mess, and people would have still been infected...

I can't believe I just defended Windows here...

I fixed hundreds, maybe thousands of machines infected with malware back in those days. Switching users to Firefox and a safe e-mail client nearly eliminated all of their issues.