I see several problems with that. One, you can't assume erosion didn't happen. Two, one rock can become something else given the right conditions... also, in this guy's case, depending on what type of rock you put. Three, it's nearly impossible to confuse because the rock would be stripped to the chemical, mineralogical core, meaning that with the right equipment, a geologist is able to tell you in what conditions a rock formed, a rough location (and depth), and if the location where it was found and the location where it actually came from are totally different, they'll also have rough ideas as of why. Four, supercontinents anyone? Rocks with the chemical print found in Africa can be found in South America.
She's not a buzzkill to us