The thing about moonstone expansions is, they put strain on a different currency- food. If you can't afford to pay the moonstones for a bigger minecart, you're spending more food per ingot than somebody with a bigger cart (because afaik, expanding the cart doesn't make it cost more food points to push either way). If you can't afford the moonstones for a bigger cooking pot, it's a lot harder to keep up the food to continue playing features- at least, if you want to do anything but toodle around in the first sword areas grinding nothing but food points. That's not as fun as trying to get crafting mats/WWs, but it's what you have to do (and no, farming doesn't quite make up for this, because it's time-gated; at least at the levels I'm at, you can't farm enough stuff to keep going until the next batch is done, not quite).
Maybe I've horribly mangled my builds for stuff, I've done that in the past before. Right now, though, it really feels like a “if you are not willing to give us real money, go jump in a lake” situation, though… which is a shame because I want to like the site but haven't real money to give atm.
(Editing to add- I'm fully aware that the site needs to make money to stay afloat, and I think that if Moonstones are something you can afford, it's 100% a good thing to buy! I just think that locking gameplay behind a paywall is much scummier than locking aesthetic items behind a paywall, that's all.)