Analysis of information sources in references of the Wikipedia article "Influence of the IBM PC on the personal computer market" in English language version.
... the real impact was in marketing— a PC with IBM's massive organization behind it. By mid-1984, estimates were that 75–85% of all software being written was targeted for the IBM PC and compatible machines.
In some ways, the most far-reaching decision made by the team that built the IBM PC was to use an open architecture, rather than one that was proprietary to IBM. That decision led to the market for add-in boards, for large numbers of third party applications, and eventually to a large number of competitors all creating "IBM-compatible" machines. ... Bill Lowe went to IBM's Corporate Management Committee in July 1980 to propose the project