That's because the owners are too embarrassed to admit they did such a thing, and it's too much effort to post a picture using a mouth stick. As far as your stress analysis, it doesn't really matter that a fatigue crack is more likely to form elsewhere if it's likely to form where you drill your hole. "I know it broke, but it could have been worse."

Depending on the blade, steel forks are a bit marginal. That's why cheap bikes have aluminum or carbon forks. Forks undergo a lot of cyclic stress. Your hole quality will be bad, and that is more likely to promote crack initiation. Use a clamp.