I don't buy the tidal forces bit.

But I do buy the planet(oid) bit. They say Earth was hit by a smaller planet(oid) and much of the heavy content fell back to what remained of the earth and the earth had a ring for a while that formed the moon, lighter than one would expect and without a strong magnetic field.

Our moon is drifting away. Eventually it will slip the bonds of earth. And then what?

All the planets are slowly moving in one direction or another, sometimes changing due to alignments. Sometimes colliding or enveloping (Jupiter). They say the Earth is only 4.5 billion years old and the Universe 13.7. That's a lot of drift time.

Maybe Mars was similarly a resultant "moon" of that shattered planet, also with a weak core.

Add my theory to yours and I think we've got a Nobel Prize in theoretical armchair slackery.