It's not storage, it's bandwidth. Most system providers, for Bad Reasons, charge a lot for egress; even relatively good ones like Cloudflare have particular payment shenanigans around video. Size uploads could help in that situation, but it's a bandaid on a bullet wound when the video still gets played a million times, y'know?
Then people are going to link to YouTube and benefit of getting lesser copies is small. The rest of media that works within a limit on a microblogging are junk.