Microsoft didn't create DOS
Besides, my point clearly wasn't who originally authored MS-DOS but rather that MS didn't even have a product to sell -let along a well engineered one- back when they first visited IBM.
Microsoft BASIC was the original Microsoft product, written by Paul Allen and Bill Gates in 1975. It was already wildly successful and the default microcomputer BASIC dialect by the time they had talks with IBM.
MS-DOS was originally 86-DOS, née QDOS, by Seattle Computer Products.
And yes, MS-DOS was originally a SCP product - however you've left out the important part: when Microsoft visited IBMs headquarters to sell their disk operating system after Digital Research struck out with IBM (though accounts regarding what happened there differ wildly depending on who you ask), Microsoft did not have a CP/M nor DOS clone at that time which is why they approached Tim Patterson of SCP and later bought the OS for a pittance compared to what Microsoft then licenced it for. Thus once again I'm completely correct to say Microsoft didn't have a product to sell.
I don't know why you and the former poster have gotten so hung up on who originally created MS-DOS since I was only discussing it's licensing to IBM. But hopefully you now understand the point I was making.
Microsoft were always a marketing first company. Even in the early days they sold BASIC and DOS before they'd even written a line of code. And Windows certainly didn't become the dominant desktop OS through being the best at engineering (in the 80s and 90s they were usually amongst the worst in terms of performance and stability).
Having good engineering and being product focused doesnt mean you'll have a successful product. In fact all too often it takes underhanded stunts to get your neck in front simply because most people are not like us, they're not engineers. So you'd be amazed at how little most people would care about what's happening here (assuming they even understand it in the first place)