Remote Data Blocks takes advantage of the block bindings API. This core WordPress API allows you to “bind” dynamic data to the attributes of core blocks, which are then reflected in the final HTML markup. Generally, this avoids the need to write and maintain custom blocks.
For a quick overview of block bindings, the announcement post is very helpful; for a deeper dive, consult the public documentation. That said, an in-depth understanding of block bindings isn’t necessary to use Remote Data Blocks: just know that the plugin is built on core, stable WordPress APIs.