What the IBM PC provided was a standard on which competition was unleashed and massive investments went into improving a common platform. Which is how all the closed proprietary alternatives got overwhelmed. Without it, we would have many weak walled gardens incompatible with each other, like we have on the smartphone market.
Listen to Linus Torvalds when he says that the PC is so easy compared to the nightmare of all those incompatible arm SOCs.
I dream of a smartphone PC.
There was an industry standard before IBM PC, based on Z80 S100 and CP/M
> What the IBM PC provided was a standard on which competition was unleashed
Entirely accidental. What really started this was the reverse engineering of the BIOS. This allowed any company to enter the market with a PC-compatible computer. IBM tried, but clean-room proved to be an effective defense.
> Without it, we would have many weak walled gardens
Kind of. There were Apple II clones with varyingly clever schemes around copying the original ROMs, and it provided slots so many manufacturers could provide hardware for the machines. Microsoft was one of them, with a Z-80 card that allowed the II to run CP/M software. Atari had a serial bus that allowed external expansion - less popular than the II, but still allowed other manufacturers to expand it. And let's not forget the ubiquitous S-100 bus, with hundreds of different companies making hardware for. In 1983 you could assemble a computer around your choice of processor, graphics (or not), IO, mass-storage, and so on.
> incompatible with each other
Kind of. Prior to MS-DOS, CP/M was the de-facto 8-bit standard for business computers. It had a multi-user version called MP/M, and versions for processors other than the 8080/85 and Z-80. In the higher end, Unix-compatible small computers started to appear - the TRS-80 model II could get a 68000 board, for instance.