The artifacts along red/blue edges in JPEG can easily be fixed without giving up chroma subsampling. Everyone recovers subsampling with linear or nearest neighbor upscaling because it's "fast".

If you take one of these subsampled images and use a proper upscaling filter, or better yet, use the Y plane for edge hinting, it'll look great.

JPEG's really not good enough for efficient 4:4:4 but I do think a newer format could handle it.