"What makes people think that Grob's Opening is so bad?"
++ It loses by force for white and it is the only move that loses by force for white.
Neither one of these statements is proven. Those AlphaZero papers are anecdotal evidence at best, not anything scientific.
They're not anecdotal evidence, they're tripe.
Anyone who knows anything about chess knows that you can't lose "by force" after the first move especially as white. It's a draw.
While I'm at it the phrase "loses by force" is such a dumb expression. If you mean "forced loss" then just say that. Unless your opponent is physically trying to stop you from playing moves "losing by force" makes no sense, it's just a dyslexic way of saying "forced loss".
"What makes people think that Grob's Opening is so bad?"
++ It loses by force for white and it is the only move that loses by force for white.
Neither one of these statements is proven. Those AlphaZero papers are anecdotal evidence at best, not anything scientific.