@aescling The argument goes that you don't always need the code in the repository for the action to be run successfully (a deploy job, something that interacts with the PR/MR like commenting, a job that consumes other jobs' test results, etc.), and I think you can just clone it with the environment key if you want? (I don't really have a preference between them, but there are reasons to make the checkout optional.)
@aescling Eh, I mean, obviously you don't, but there are a bunch of features (https://github.com/actions/checkout?tab=readme-ov-file#usage) so you need *some* scripting language, and arguably TypeScript is easier to write correctly (and test) than Bourne [Again] Shell. (They also document why they moved it out of the runner itself: https://github.com/actions/checkout/blob/main/adrs/0153-checkout-v2.md#port-to-typescript, which mostly seems to say that it's not really about the action itself so much as the rest of the ecosystem.)