I do realize, I can myself download the step (or whichever format you choose) files from the link in the readme, this is true, but it is still "just" a link, and it can go away (dissapear) anytime, this is for future-proofing, archival purposes.
We never know when onshape will go down or even put this data under a paywall, and make this data unrecoverable.
Thank you.
I realize this can be a big file, so you can also include it in github releases as opposed to in git version control