I couldn't help noticing that, on my Stack Overflow profile, the reputation graph in the summary section doesn't show on mobile or portrait devices. I feel that there's easily space to fit the graph on the mobile page.
I have an idea on how to do this:
You could add a settings option to turn on the graph on all devices. I understand that this would be a lot of work for SO (I'm a website developer myself), but that (at least for me) it would be very worth it.
I noticed that when my device is turned into landscape mode (and the screen is wide enough), the graph shows.
To be clear, I'm not talking about the
Reputation > Graph tab, I'm talking about the 4-year reputation graph shown on the summary tab: