I've long switched to Emacs/Org, but used JupyterLab extensively before (as a data scientist). It's way more powerful than vanilla notebooks since you can open notebooks/code/related side-by-side, easier to extend (with lab extensions), etc.

I always thought people only still used vanilla notebooks because that's what people say they use, e.g. "I work with Jupyter notebooks" (even though that may well be in JupyterLab). So most regular users wouldn't necessarily know about JupyterLab.