I think you misunderstand the job listing though. Apple requesting minimum qualifications of Excel proficiency doesn’t mean that Apple is using Excel. It just means that Excel proficiency is minimum skills they are looking for. If you are proficient in Excel, those same skills can be transferred over to a different suite of software services.
There is no way that Apple is using Excel for its global accounting, tax, compliance and regulatory requirements. Apple uses SAP (and/or other ERPs, but seemingly SAP primarily).
Excel is fine for many things (I have Excel open right now), but it’s not a replacement for an actual ERP. And it’s especially not a replacement for an actual ERP when we are talking about one of the largest companies to ever exist.