By that rationale isn't Obsidian itself a language on top of Markdown?

Being able to view your Markdown files as a graph or show a list of backlinks is possible because Obsidian has some JavaScript to do that. Previously one could write other views with plugins, but bases make it easier for non-technical folks to create views.

The views are described in human-readable YAML, so recreating them in another tool is possible. That's effectively what many people are doing if they're converting views from Dataview to Bases. There are already tools that automate this: https://github.com/Quorafind/Bases-Toolbox

The output of views can also be converted to plain Markdown tables or CSV.

If you boil it down, bases are a visualization layer that is in service of creating and editing Markdown files — and that's what Obsidian has been since the start.

If you're not interested in this feature set you can disable Bases in core plugins :)