All IBM PC clones had (or emulated) the same 8253 timer, 8259 PIC, 8237 DMA controller, 8042 keyboard controller, CMOS RTC, 8250/16550 serial port, standard IDE/PATA, standard framebuffer addresses, standard PCI and ISA register addresses, FPU was always at IRQ13, mouse at IRQ12, RTC at IRQ8, LPT at 0x378, PC speaker at 0x61, etc.

All this doesn't require any enumeration and was still standard until BIOS/CSM was removed. PCs could use the same IDE driver for 30 years of hardware! All chipsets were compatible, from 386 to today's SATA in compatibility mode.

ARM made the mistake of not standardizing anything beside CPU instructions (and even those aren't always the same - see the mess armv7 created with thumb, thumb-ee, simd, neon, crypto acceleration, etc.). Of course it needs enumeration. But x86 is now catching up with the mess. Just wait...

Enumeration instead of standardized hw is bad, but I prefer the least worse device tree.