While I agree, many of my team unfortunately see it slightly different but use Github because of issues like lag of the Graphite UI when loading / opening a PR, no ability to search for PRs or look at PRs from a specific author unless you change the filters of your dashboard (and no, the shortcut to search for a PR of a person doesn't work at all), the merge queue being not being powerful enough to justify changing Github merges to also use it, automations, inbox and notifications are all available on Github as well, etc. -- Unfortunately, the features that you list that are clearly a benefit, are not strong enough to make people really engage because the workflow that you always do is slowing folks down (e.g. reviewing and loading PRs; getting an overview of open PRs (that you are not assigned as reviewer), etc. you need to go back to github anyways)...
Long-story short. Yes, I agree that there are many features but what are the plans to keep the lazy engineer to leave their well-known environment if the first thing they need to do is overcome some things that are actually worse to finally get to the improvements.... (and I know its subjective. I personally use graphite for 99% of my stuff but its about a full engineering organization and not my preference...)