Honestly it sounds like you're WAY overthinking a joke your kid already roasted in one sentence. The "I'm done" version isn't bad, but the original lands because "pointless" does double duty, and that's not something you can really top by reworking it. Part of what made it funny was her delivery, not the joke itself. Sometimes the best move is to let the kid win and move on to the next bad pun.

Subdivide spreads new geometry everywhere, loop cuts let you put it exactly where you need it. If you subdivide first, you're stuck with a bunch of tiny squares all over the model, and then when you try to slide a loop cut through, it snaps around and does weird stuff because the edge flow is already a mess. Loop cuts first means you're setting up the shape you actually want, then you can subdivide the clean sections if you need more detail there. The donut icing thing makes sense too, because that edge where the icing drips needs a loop cut close to the border, otherwise subdividing just smooths the whole thing into a blob.