This makes 0 sense

Ground news links all of their sources on a per article basis and you can simply scroll left/right through each news source. And you can add your own sources!

You didn't address the meat of my argument. The sources are irrelevant. They try to tell you the media bias which can itself be biased and gamed and which (I think) leads to readers not critically examining sources for themselves.

If somebody is going to be uncritical I don't see how any of this actually helps, but that's totally on them.

I'm not going to argue with them saying that Fox News is right wing or that MSNBC is more left wing. "Duh".

Maybe we're looking at this from a different angle, or maybe we just use the service in different ways.

The "bias" part that is relevant is showing you the difference in headline and contents between dozens or hundreds or thousands based on historical leanings of the news org, and which ones are even reporting on a particular topic.

It's not saying a particular article leans a particular way, it's saying the source does.

I don’t get the sense that Ground News is trying to influence what news stories I select; I think they are presenting metadata that allow me to look at the story from my preferred frame of reference and from the opposing frame of reference. I find it valuable; you might not.

I think that the media bias ratings on Ground News are slightly biased and the factuality ratings are highly biased, not intentionally but due to flawed methodology of their sources. I have contacted their support to raise that issue.

I still find the site tries really hard to make you aware of your own predilections, and I think it does well as that, and if you find yourself gravitating towards one set of sources you can always sample the “other side”.

I agree that left-right doesn’t capture the richness of American politics but for better or worse they are convenient labels for our two party system.