I genuinely would like to hear about a more important piece of software for businesses. Or more used. In those respects I'd have to agree with each of those statements.
I think "for businesses" is probably the caveat here. It feels like a trope to mention it at this point, but I think the world would suffer greater consequences if, say, the Linux kernel broke.
I'd also argue that Excel isn't really the most "powerful" per se, but the most accessible and convenient for sure.
SAP or Salesforce is often the critical piece of software in many an organization. My current assignment (I don't work with SAP though, thankfully) is an energy company with ~3 million customers, each and everyone's data is managed in SAP along energy usage, billing/invoicing, the works. Small army of people managing and maintaining it, too.
I'd also argue that Excel isn't really the most "powerful" per se, but the most accessible and convenient for sure.