Apple has always had one of the worst cases of “not invented here” syndrome. If a third party vendor comes out with a piece of hardware that works with a Mac (example: RAM chips that extend your RAM capacity far beyond original Apple-published specs), Apple will remain officially ignorant and not tell you about it if you call and ask.
re: compatibility, though: while it’s true that Apple hasn’t always used industry-standard hardware, it’s also true that this is often because those standards didn’t exist until after Apple had its own implementation in place, an implementation that PCs could have gone with but didn’t. For example, the Macintosh 3.5" floppy drive with auto-eject and using the low-level GCR format and variable-speed drive predated the PC implementation with manual eject button and low-level MFM format with constant-speed drive. Had the PC world used the same format and drive type, Macs and PCs could have read each other’s floppies a lot sooner than they did (Apple eventually adopted MFM for hi-density diskettes and from then on their drives could read both lo-density and hi-density MFM floppies, including PC floppies, while being backwards-compatible with GCR lo-density Mac floppies). And NuBus could have been an industry standard for expansion cards — it sure beat holy hell out of ISA slots — but the PC world didn’t adopt it so it wasn’t until the PCI era that both platforms could use the same expansion cards. Similarly, ADB was pretty nifty for its time, and yet the PC world slogged along with a dedicated mouse port and a dedicated keyboard port and other peripherals being added sometimes to the printer port and sometimes to a COM port, often with no pass-through for subsequent devices, when they could have embraced ADB instead and let PC users daisy-chain their input and output devices. Nor would the PC world have failed to benefit from offering a standard external SCSI port. The price of SCSI devices would have plummeted and PC users wouldn’t have been stuck with such slow & unreliable things as the Iomega printer-port Zip drive.
On the other hand, I can’t for the life of me explain why Macs (and Apple monitors) for so long had that DB-15 video connector instead of the standard, smaller, more elegant VGA.