Piltdown was rejected 70 years ago, so hardly a current example. Kamitakamori was someone taking legitimately old artifacts and putting them in other places. You can detect that (as people did), but it's much less obvious than you're suggesting.

There are also numerous examples where physical artifacts haven't been immediately accepted. The white sands footprints. Monte Verde II. Others like Monte Verde I, Buttermilk Creek, and Cooper's ferry still aren't accepted despite physical evidence.

Consensus generally has high standards for anything that pushes boundaries. It's very easy to construct an "obvious" explanation that's totally wrong. We call these "just-so" stories. A narrative that's supported by physical evidence is a lot more verifiable.