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[Eurytus]

Explain why it is ludicrous without resorting to your own private prejudice. (I realise you did this earlier, using examples such as quality of acting, etc, but this proved inconclusive.)

You found it inconclusive, I personally don't.
By any standard you like the acting in Star Wars is subpar. It certainly can't be described as worthy of merit. Of the three leads only one, Harrison Ford, is any sort of actor. As their subsequent careers amply proved.
Some of the dialogue is shocking.
The directing is functional.
The storyline is very basic indeed, practically a fairy tale.

Now none of those things in isolation might prevent it from being the best film of all time but can any film suffer all these flaws and still be the best film of all time?

Better than the Seven Samurai?
Better than the Godfather?
Better than The Shawshank Redemption?

For me the answer is no to all those. And I could add many more.

I mean take the FOTR.
Is the acting better than Star Wars? Yes.
Is the dialogue better? Yes
Is the story better? Yes
Is the directing better? Yes

I yet I could almost guarantee which of the two would top a "best of" poll.