I think this has to be it. No way Marvel wants "Spider man card game" to turn up Arena first in search results over Marvel Snap. And this confused me when they first announced a Marvel set given that Snap was already a thing.
I think this is a win for Arena, but it will be super confusing not having the same card names/artwork across paper and digital especially for anyone who plays both. Have to learn everything twice I guess. Deck list importing just got a lot harder too.
I think this is just insane and super confusing. Another huge indicator that the Marvel sets (and probably all of UB) should have never entered Standard. Just make them Commander-only, and you never have this problem. They could release certain UB sets to Arena and not have to push the others if there were digital licensing issues.
Now, instead, we have a huge break in paper/digital that will presumably last and repeat forever. This makes deck list sharing and importing more difficult. This makes watching the game much more difficult. This makes learning the limited environment much more difficult. This is just way confusing and way stupid imo. I guess it's a huge win for Arena players who didn't want Marvel in the game but that's about the only positive I can come up with.