It happened. Let me see a map of the fall line...okay, I think they're close to the fall line, but to the north of it. As a rule of thumb, you have sedimentary rocks on the surface south of the fall line in the US due to, well, it being filled up with sediments. North of the fall line you have non-sedimentary rocks close to the surface. So these boulders were where you'd expect to find non-sedimentary rocks, but they were isolated in one area. Plus, they had markings on them that were interpreted to be abrasions from being pushed along by a glacier. So the idea was that the boulders were carried there by a glacier, and when the glacier melted, there the boulders dropped.
At what point geologists determined the marks were caused by logging chains I can't say, but I think it was in the 1970s. It would be interesting to know how they made that determination. Anyway, when geologists determined the marks were manmade, that ended the glacier theory.
I remember the discussion, at least where it attracted the attention of the media. The question was, of course, was there a glacier in Georgia, and likely at what time? So when geologists determined the marks were caused by logging chains, there was amusement in the media.
Now, speaking as someone who studied geology, you say that would be really stupid and sloppy. Perhaps. I'm no geologist. Yet I do know hindsight always has perfect vision. What seems obvious now isn't always obvious then.