The vast majority of git repos are tiny so there is no gain. And most of the benefits of git require history to be downloaded. You’d be better off clicking the download zip button on the git host if you only care about the latest version.
Not the repo I work with at work on the daily. It’s got some 30k commits and it’s something like 200 megs or more.
That's really a non issue still. You download it once which for most people is still really quick, and then benefit from the history going forward. I have only seen it as an issue on massive repos like Android where you only really care about compiling from source and not doing actual development.
Sorry, if the entire repo can fit in RAM on a low-end consumer PC, it's not large.