Why do people insist on saying this? Yes, it might be the most likely reason, but Occam's Razor is not a law. It's more of a saying. Why are people repeating it as if it is always true?
I'm using it as a shorthand for: "Here is a perfectly reasonable explanation that fits the facts. The other given explanation requires the conjunction of multiple unlikely things and I see no evidence favoring it. I believe the other explanation is sufficiently unlikely that there's not much point speculating about it."
Why do people insist on saying this? Yes, it might be the most likely reason, but Occam's Razor is not a law. It's more of a saying. Why are people repeating it as if it is always true?