It was MS who forced it big; they wanted standardisation on both professional and 'home computers'; IBM PC (clones) and MSX[0] respectively, both running MS software. MSX failed, but the idea was the same; a hardware standard everyone would adhere to and MS would have the software for. MS was a huge factor in making that happen; no-one knows what would've happened if they would not have done that.
“The idea of acquiring Atari was considered, but rejected in favor of a proposal by Lowe that by forming an independent internal working group and abandoning all traditional IBM methods, a design could be delivered within a year, and a prototype within 30 days. The prototype worked poorly, but was presented with a detailed business plan which proposed that the new computer have an open architecture, use non-proprietary components and software, and be sold through retail stores, all contrary to IBM practice”
That was before even the choice for a CPU was made (makes me wonder how prototypical that prototype was), so I don’t see how Microsoft would have been involved at the time.
When IBM lost control of the PC market when Compaq and other clones started coming out and their proprietary PS/2 PCs were rejected by the market, the power to define what a PC was fell into the hands of Microsoft, who still holds it today through their Windows hardware certification program. It is Microsoft who is keeping PC hardware open, albeit probably more because of fear of more anti-trust scrutiny than any altruistic motives.
Reality was more that MS /benefited/ from the IBM-PC clone market rather than MS /caused/ the IBM-PC clone market.
IBM gets some credit, for making the IBM-PC with commodity components, which set the stage. But it was the clone makers (with Compaq being first, but certainly not last) that ultimately caused the standardization around the IBM-PC style systems. And the clone makers were driven by the fact that, at the time, the market (esp. businesses supplying their users) wanted to be compatible with the IBM-PC, while saving costs over buying an actual IBM-PC from IBM. MS benefited from the explosion in sales of IBM-PC clones by being the OS provider for the IBM-PC, so as a clone maker, to be fully compatible, you also needed MS's OS on your clone.
The standardization process occurred some years later once the market had clearly moved towards the IBM-PC architecture. And MS likely had some hand in guiding that process, given their monopoly at that time in the OS that every clone maker wanted to use. But by the time MS was powerful enough to begin any guiding (or "forcing") the market itself had already "standardized" because of the huge sales potential of being "IBM compatible".
[0] https://en.wikipedia.org/wiki/MSX