re: I expect that's probably the case...
You don't want my opinion on the knowledge level of most film reviewers.
I can also verify several stories of people walking out of Apollo 13 regarding the fact fact that the astronauts were rescued ("I KNEW they would be!").
Hey, who needs books when you've got all sorts of easy to use gadgets that do the thinking for you?
Going back to the original 1896 novel WOTW, if the germs hadn't gotten the Martians, it's very likely they would have taken over Earth, because little else seemed to be stopping them and reinforcements were probably on the way.