Hermann Hauser is right in that Acorn had superior machines than the PC and may lament the lack of success. But my personal recollection of time was that the IBM PC had the killer application and killer extra hardware. i.e. It had the IRMA card that allowed the PC to be used as cheap IBM mainframe terminal and to download mainframe data for use in a LOTUS 123 spreadsheet. You could not go into any reasonable sized company in the mid to late 1980 and not find that every department had their IBM PC and they were downloading mainframe data for analyis, as the prices dropped they would replace all their mainframe terminals with PC and IRMA cards. IBM mainframe ( Or compatibles ) where totally dominate at the time so the IBM PC cornered the Commercial market. As PC's became more affordable like for real home use, people tended to go for the same as what they had at work ( ability to bring work home etc ).
No other company Apple, Acorn etc understood the significance of IBM Mainframe access for commercial use of the PC. This is one of the main reasons why the IBM compatible succeeded in my opinion.