Many biblical archaeologists start with a premise (the events in the Bible are real) and then sift the data for the parts that support their premise and abandon those that don't.
Doesn't most archeology of historical times follow this sort of paradigm? Admittedly, archeology has evolved, but practice has often been to follow a historical document, and try to support it.
The Bible and BoM are just two examples where the "historical document" was not so much historical.