There are many reasons to reproduce papers, it doesn’t matter if the author is unquestionably correct. One is to establish that they actually did what they said they did. What if the authors stole this result? It’s certainly happened before. If we don’t accept students divining solutions, why should we accept that from scholars?

Another is for posterity and for future generations. If I give the paper you cited to a student, they can be wowed at its brevity and impressed by its genius, but they learn nothing.

I get you’re trying to prove your point but all you’ve done is solidify my position in my mind that literature reviews are essential to good research. You’ve given me a great topic for my talk to our incoming class of Ph.D. students in a couple weeks, so thanks for that, I mean it. Cheers.