While true, it wasn't always that way. The IBM PC with the BIOS was basicaly one of the first layers you'd have to be compatible with, and up to UEFI systems with CSM for BIOS emulation, it's been supported for about 30 years.
There was a time where the chipset did a lot more than it does now. Right now, it's the PCH or whatever it's called, and you even have those SoC's where you don't even need that anymore. You used to have the possibility of a standard BIOS with a chipset from someone else (SiS for example) and audio from someone else, as well as PCI controllers, PICs, RTCs, HBAs, UARTs, and CPU's. Or have an Intel chipset with a non-Intel CPU, also possible. You could even make a complete x86 system with no Intel chip inside (pun intended). Right now, that's something you probably can only do with an AMD system and that's about it.
It's true that Intel is by far the largest supplier of x86 chips, and so you get some level of "standardization" with things like Intel HD Audio. But that's more the effect of a monopoly than anything else. Competition breeds fragmentation, but given the choice I'd rather have competition.
[1]: https://www.techpowerup.com/img/15-08-18/77a.jpg