It wasn't because you were all together in the same room, it's because you were communicating effectively and you're assuming there is no way to replicate that level of effective communication without being in the same room.
With proper tools and training, everything you did in that room could have been done over the internet instead. There are communal whiteboarding apps, collaborative code editing apps, amazingly expressive chat apps like Slack, not to mention good old fashioned audio/video chat tools.
It can be done. It is done frequently, every day. It makes me sad to see so many people on a place like Hackers News, dedicated to building the internet's Next Big Thing repeatedly claim that it's not possible to collaborate as effectively on the internet.
It's truly ironic.