What do you have against Obsidian's business model and what better one do you imagine?
If they created an open source version I could self-host, I would happily adopt it. Frankly it looks beautiful and is only missing easy file integration. But they don't because it would cause them to lose a vast source of value they provide to their customers (providing proxies and servers for people to access their data remotely).
The only part of their business model you can't go around is the fact that they're not FOSS, and for business use you need a business license. I personally find the terms quite acceptable (only apply if you work in a for profit place with more than two employees and more than X revenue), and the price is good value for money for me.