Au contraire, Tanenbaum was 100% right. And porting linux to the first new architectures turned up a ton of hard-to-fix dependencies on x86, fortunately the UNIX system call interfaces were all copied from more mature instances and lived on unaffected.

Just because you can succeed despite ignoring your professor's advice doesn't mean the advice wasn't sound.

Linux started x86 only, but it was soon ported to other architectures. I was running it on SPARC just a couple years later.