this is not really true for open source, I think. since it's collaborative I think it's fair to expect people to be able to open a GitHub link
This is very much a Chesterton's fence topic, I think. Linux developers have settled on a workflow that works for them, and if you want to get time from the people who are doing the bulk of the work it's fair to expect you to work within their requests.
Git itself is a satellite project of the Linux kernel. It can work without the web at all. That someone EEE’d it so hard that even Microsoft couldn’t resist is no reason to expect the kernel devs to change their workflow.