Doesn’t “sufficient randomness in observations” just mean that you split the possible worlds further by conditional probability of observations given actual world-state? You can still eliminate the ones where the observers don’t observe what you observed.
For example “I observe that the calculator says NO” doesn’t let you eliminate worlds where the correct answer is YES, but it does let you eliminate all worlds where you observe that the calculator says YES. So “notice that you (an observer who sees NO) exist; exclude all possible worlds where you don’t exist (because observers in that world see YES); renormalize” still does some work.
Doesn’t “sufficient randomness in observations” just mean that you split the possible worlds further by conditional probability of observations given actual world-state? You can still eliminate the ones where the observers don’t observe what you observed.
For example “I observe that the calculator says NO” doesn’t let you eliminate worlds where the correct answer is YES, but it does let you eliminate all worlds where you observe that the calculator says YES. So “notice that you (an observer who sees NO) exist; exclude all possible worlds where you don’t exist (because observers in that world see YES); renormalize” still does some work.