I had a similar experience -- went to a new dentist, they found two "cavities", tried to hard-sell me into getting them filled right then. I declined, never went back to that practice, and 10 years later my teeth are perfectly fine.
#notalldentists, of course, but there are certainly unscrupulous ones out there, and not just a few.
That was apparently their purpose back when we lost teeth more regularly - it's only with modern dentistry that they become a problem for being "extra"
It was not an intentional replacement or anything the dentist did. I had my back molars pulled and then a few years later while trying to start flossing again I noticed they were back and basically in the same position. I doubted myself for a moment if my memory was failing. Just such a slow long process.
#notalldentists, of course, but there are certainly unscrupulous ones out there, and not just a few.