I had the same confusion and re-read the article. Best I can understand, what they're trying to say is that it could be used without a build step in the sense that you could just manipulate the database's AST-like structure directly instead of compiling code, and it would be basically incrementally "compiling" each unit as you edit instead of interpreting a code file. But of course that's not a very ergonomic way to do it so there is a language on top, that they used as an example to show off the language.
I can see this being useful for implementing alternative editing interfaces besides just writing code textually. For example, flow-based visual programming or something like that. Adding and connecting nodes in a visual interface would each be small updates to the database, and then there would never be a "build step" because the database you've been editing is already the AST that could either be interpreted or compiled. So it only really does away with the parser, but that doesn't seem revolutionary to me, other languages can already do that. I might be missing something still.
I can see this being useful for implementing alternative editing interfaces besides just writing code textually. For example, flow-based visual programming or something like that. Adding and connecting nodes in a visual interface would each be small updates to the database, and then there would never be a "build step" because the database you've been editing is already the AST that could either be interpreted or compiled. So it only really does away with the parser, but that doesn't seem revolutionary to me, other languages can already do that. I might be missing something still.