Because it's called suspension of disbelief. Suspension in the sense of putting something temporarily on hold. While reading or watching a story, we choose to suspend our knowledge that it's unreal; but once the story's over, we resume disbelief in its reality, because if we didn't, we'd be delusional. (Like those people back in 1964 who sent the Coast Guard telegrams demanding to know why they didn't send a ship to rescue the seven stranded castaways of the S.S. Minnow.) I am not watching a work of fiction when I post in this thread; I am back in reality and talking about the larger scientific ideas that are raised by a real-world discussion about a work of fiction.
And I'm not just talking about whether the show makes sense. The show is just the starting point for a conversation about bigger ideas. That's the cool thing about speculative fiction -- the fact that it touches on so many ideas that are bigger than any one story, on larger themes of the nature of existence and the workings of the universe that are explored in different ways by many different SF works, as well as being addressed by real science. So a conversation that begins with a single episode of a single show can blossom into a dialogue about the universe as a whole, about the larger nature of reality itself.
More to the point, you're mistaking my reaction to a specific thing for a more general reaction. I wasn't saying I don't believe in any explanation for what's in the show, I'm expressing my problems with the specific idea that anything that happens in a story about alternate realities can be justified by invoking the "Anything can happen in an infinite multiverse rule." I find that particular model to be logically flawed for reasons that I've explained. There is no reason why that critique should be presumed to apply to other models, because my whole point is that I would prefer another model.
I feel a bit too old for that.
