I think that when you look up a deck on MTG Goldfish and see "Online: $250- Paper: $25,000," that's going to inevitably lead to the online metagame being substantially larger and therefore moving faster, becoming more optimized, etc. than the paper metagame. That doesn't necessarily mean that Vintage is fundamentally a digital format now--local metagames are just different from the overall metagame. Online discussions focus on the online metagame because it's something that is the same for everybody, but that doesn't mean you can't play something outside of that and do well and have fun at your local paper tournament.
My point here is that when we measure the format from MTGO we get Thorn restricted over Sphere. I would argue that Chalice may need to come off the list to help unpowered decks but that goes down the B&R rabbit hole.
Leaving aside the specific question of whether Thorn or Sphere is the more appropriate target for restriction, is this not the right result? Many more people are able to play Vintage online than in paper, both because of the expense and because of paper Vintage events are just not very common. Most of the paper events that do exist allow at least ten proxies. The vast majority of people playing Vintage are playing with decks that are appropriately powered. Shouldn't B&R policy address that reality?