The GitHub linear view that shows no graph is a real problem on my team, because at least one team member has no idea when they are creating a complex, unbisectable graph with their merge commits and no-message submodule updates.
To them the timeline is just a linear sequence of what everyone has been working on recently, mixed together. They do understand feature branches, but then they randomly merge their branches in progress and the result is still a mess somehow.
To me, seeing the `git log --graph`, it's a difficult to understand mess with redundant micro-branches and micro-merges. Randomly unrelated file changes and even file deletions also occur - `git commit` might as well mean "copy my working directory into the repo". As a result, the main branch quality varies and cannot be trusted from one day to the next.
The difference between us is I actually look at the repo history, I look at my commits before I commit them. They appear to commit things without even knowing what's going in, and don't look afterwards, as it's a surprise to them when I complain about things like a file deletion.
GitHub's commit history view is part of the problem, because its presented as if it's the main, primary way to look at the history. It's not the problem, but it makes things worse. Better visualisation tools would help, but for now everyone has their own "pet way" of using Git, I lack the social capital to convince anyone to do better, and the gravity of GitHub as "the way" makes it difficult to get anyone to care about any alternative way of viewing the repo. "It's what everyone uses".
GitHub issues similarly suck as a project management tool; guess what we're using.