Probably different for each person what they’d want there. For me it would make total sense to have memes show in my profile gallery, as that’s primarily what I post, and probably what people are looking for if they open my gallery. But if I reply to someone else’s post with a gif or even a random meme, I don’t need that cluttering up my gallery. Or if I’m posting a screenshot of something like a settings page, or bitcoin price chart, or news headline, etc, with a text post the I also don’t want that in my gallery.