Why doesn't home-assistant.io use Roboto?

Roboto is the standard font in Home Assistant. The frontend uses it, the setup page uses it, even the initial landing page uses it. But home-assistant.io doesn’t.
Is there a good reason for this? Would it be okay to add Roboto in a PR?
With Roboto (I also disabled the shadows):


Without Roboto (how it currently is - note the misalignment caused by Helvetica):