Yeah, a 20+ years file format doesn't do compression between frames, who would have thought...
As I wrote in a different comment the actual reason is lossy jpeg compression, not intra frame compression.
Yeah, for pictures jpeg is much better (and smaller) than gif.
Not to mention in several gifs they really reduce the quality to have a smaller file size
Yeah, a 20+ years file format doesn't do compression between frames, who would have thought...