I believe the reasoning for certification is more relevant to the value add to the business rather than the third party audit companies themselves. As in, why would an organization want third party certification? For some business sectors it's a prerequisite for business (IATF for automotive for example), or at least continued business. In these cases it's not that the organization wants certification, it's that it needs it.
Another example would be ISO 9001; it's sold under the marketing that it's applicable to all organizations regardless of context, sector or size. But why would a business that sells directly to the general public be interested in certification to 9001? Only if they believe it would make their business better.
It depends on where the motivation for certification comes from, within the organization or outside. I believe an organization will find much more value if there's internal motivation rather than a customer pushing for a certification.
Organizations, big and small, have existed and thrived long before third party audit companies existed.