There are a few reasons why no PCI multi I/O card exists. Multi I/O cards, and the Super I/O chips that followed them, integrate and implement various legacy hardware of the original PC and PC/AT, depending on what the motherboard chipset lacked.
- When PCI first appeared, computers still had ISA slots, so ISA Multi I/O worked fine.
- When the ATX standard for motherboards took over from the AT standard, ISA slots were still around, but the legacy ports moved onto the motherboard directly, so no need for a card.
- Components such as the keyboard/mouse controller, real-time clock, floppy disk controller, serial ports, and the parallel port were all originally ISA devices, so for compatibility reasons, they stay on the ISA/LPC bus. Even very recent motherboards still have a portion of the LPC bus implemented, despite not having ISA slots.
Of course, there are PCI cards that provide each of these legacy ports for legacy-free computers (except for the clock, which is always integrated), but I'm not aware of a PCI card that supplies all of them. The most I've seen is a combo serial/parallel card. For the parallel ports and floppy disk controller PCI cards, do they even work in DOS? DOS (and the default Windows 9x drivers) are expecting these devices to speak ISA, and for the parallel ports and floppy controller especially, that means ISA DMA and ISA IRQs.