Gifs are extremely efficient though. There is only downloading and no decoding necessary to play it back so it has no impact on your CPU. If you have a screen full of 1000 GIFs then your CPU won’t start melting. Try playing 1000 video files on your computer no matter how small they are.
However, there is no reason for a 50mb GIF to exist. If you actually have something that is longer than a few seconds you should not use GIF.
It can be an argument if you want, but it seems more like a discussion to me. I refute the idea that gifs are horrible and obsolete. You even give a use case in your post. If I have a 1 second looping image I’d much rather use a gif than a video format. So I believe they should work on Lemmy. The rest of the internet has no problem supporting this format.