I think if these other theories had explanations as well crystallized as the action of gravity, the other poster would not object to presenting them. It's not an interesting analogy, it's a trick to legitimize hand waving about other things.

(we may not fully understand the mechanisms by which gravity acts, but we understand the effect it has quite well, to the point where we can GPS for instance, because we can precisely account for the very small differences in the way time passes in orbit)