Fine tuning for the earth might be able to be explained away most easily, like you said. Fine tuning for the universe, though...

Firstly, we have zero evidence for multiverse. Some scientists even argue that the idea is untestable and unfalsifiable.

When you said:

> there must be a graveyard of universes where the parameters just didn't work out for life

You just committed inverse gambler's fallacy. It's like:

> You wake up with amnesia, with no clue as to how you got where you are. In front of you is a monkey bashing away on a typewriter, writing perfect English. This clearly requires explanation. You might think: “Maybe I’m dreaming … maybe this is a trained monkey … maybe it’s a robot.” What you would not think is “There must be lots of other monkeys around here, mostly writing nonsense.” You wouldn’t think this because what needs explaining is why this monkey—the only one you’ve actually observed—is writing English, and postulating other monkeys doesn’t explain what this monkey is doing.

— https://www.scientificamerican.com/article/our-improbable-ex...