I think it's one of those almost no brainer conclusions. In 1986, the IBM clone market was just taking off, and everybody and his uncle, second cousin, the in-laws, and the guy down the road was starting to build clones, all buying their OS from Microsoft, who had a monopoly position on the PC operating system that would run the majority of the software that was being written for office applications.
People with real money to invest were clamoring to be allowed to be part of the IPO purchase, but those being allowed in were very select. With that level of excitement, you could buy in the morning at the IPO price, and sell before close of market in the afternoon and double or triple your money. Brokerages reserve IPO offerings only for the very best clients. My friend was lucky to know someone who could put her on the list. Her piddly $25k was not generally enough to even consider for an IPO participant. I gather she might have been dating someone at Microsoft at the time.
That Third Party Software near monopoly, JMHO, was the real cause of MS dominance.
I quite literally had no choice at all as a Mechanical Engineer (and most every other field) during the 80's if I wanted to run a Computer Aided Design package but run MS, and that dominance continues to at least within the last five years. (I'd pretty well dropped out of Engineering about the time The 0 got into office, so that figure might be lower.)
Back in the 80's, it wasn't really that big a deal. What people have to pay and do to get those CAD programs to play nice with crap like Win10 makes me wish I hadn't given all of my drafting equipment to that damn museum.
Oh, well. I can still do a pretty good freehand sketch. Now all I've gotta do is find a machinist to make some magic.