My comment was in context of existing business infrastructure. You're right that most of us don't have a fax machine, but many organizations still do and therefore it can be very convenient for B2B communication. And in the case of orgs that want faxes but you don't have one, ifax is a thing as well.

I'm not making an argument for faxes, I'm just saying for an outdated technology it's stayed quite useful in the modern era.