I'm not really familiar with Roam as I'm not interested in a non open source tool for this type of app (why I am more interested in what you're doing). What are block references?

I guess I can see perf becoming an issue for a company wide knowledge base or a wikipedia type of thing but for a personal knowledge base which is my main use case currently I'm not clear it's necessary to have a real database and the benefits of just a bunch of markdown files are more compelling to me right now. Maybe that would change if my knowledge base got big enough or my needs more complex regarding links and references.