In fairness the decision was made in 2009. I still don’t think it was the right decision but it feels a lot more understandable to have made that choice when looking at the frameworks available in 09 rather than 2020.
I never worked at Asana but I heard it was both, it had code sharing between client and server, some server-side javascript before node.js (I think it was based on JSC) and something similar to isomorphic javascript before this term was coined by Airbnb. If you look at Meteor, a lot of similar ideas migrated there.