I use logseq + MarkText like that. Logseq provides the indexing for fast searches and let's you link anything with anything. But, I use MarkText for documents or when I want to work in raw markdown. And, I use them together, because the current version of Logseq is all markdown files you can open both from your filesystem and from within Logseq (open with external app).
I'm concerned about the next major release of Logseq, which will put it in a database. In theory, it will increase perf and scalability. But, my flow requires a lot of filesystem integration between tools, so I'm not sure that will work for me. But, the current Logseq 10.x is great with my current flow.