That's kind of like saying in 1999 that Google is really in the business of providing custom search bars to companies' web sites. They were (and maybe still are

That's kind of like saying in 1999 that Google is really in the business of providing custom search bars to companies' web sites. They were (and maybe still are) providing these custom search bars but they didn't become a separate product because search is "really just one thing". And similarly LLM output only seems unique. Everything a company can do to customize LLM output can be done by their customers as well since it's all "prompt engineering" (simplistic stuff plus some voodoo).