I don't disagree, but let's not blur the lines here between people who use computers professionally and people who use computers as an appliance.
We could have had an iOS-like security model on Windows for the majority of unassuming retail customers and I don't think it would have made a single jot of difference to wider flourishing.
(In fact, for various reasons, I would wager that we'd have a more mature technology sector. Don't underestimate the damage caused by malware to consumer trust.)
Web development as we know it would not exist. Microsoft would have banned competing browser engines (as is the case on iOS) and IE6 would have had 90% market share. The preferred way of doing active content would be ActiveX.
That's still a huge majority of PCs. The self-built PC has always been a bit of a market anomaly; people don't have self-built Macs and self-built cars are a truly tiny number.
And I'm working on the assumption that this would have applied decades ago, when there weren't quite so many viable alternatives to the PC and Microsoft was the terrifying market monopolist.
We could have had an iOS-like security model on Windows for the majority of unassuming retail customers and I don't think it would have made a single jot of difference to wider flourishing.
(In fact, for various reasons, I would wager that we'd have a more mature technology sector. Don't underestimate the damage caused by malware to consumer trust.)