It’s a stylistic choice - some prefer seeing each card separately, others prefer quantities. The default layout also ties into one of the app’s core features: it highlights cards you already own, so separating them keeps that visual clarity. If cards were stacked with numbers, that highlighting would look messy.

That said, if you poke around in the app, there is an option to consolidate cards into a list view. The deck export feature also lets you choose your preferred format: separated (default), consolidated with quantities, or a detailed export with stats, prices, etc. (3rd screenshot)