Honorable mention: https://text.npr.org/
Not technically plaintext (in the MIME type sense), but still very lightweight, especially when compared to other news sites.
Also:
https://lite.cnn.com/
I read these two all the time. I wish nytimes.com came in a text version, I hate the move to video. I was raised on newspapers not mtv...
As a long time subscriber the move to video has been pretty painful. In general the flow of stories has changed so much that I miss more news than I see in the NYT.