The only advantage of gif I know of is that the creator of the asset has some control of the playback on the presentation platform. Other than this, it is a technically sub-optimal format. But no other formats support the creator control aspect.
You might want to display media supplied by users.
Convert a video of black video to mp4 and gif, both will be lossless.
Whilst some gifs are not compressed it appears to be niche for them to not have been. Or for the creator of the gif to have not constrained themselves during the creation process.
Perhaps important for NFT creators. Whilst not overly concerning themselves with the resources involved, they shouldn't be troubled by file size either.