To clarify, this means that of the many servers Dreamhost has, only one is down, not that Dreamhost shared hosting is just one server.

And I can confirm that the downtime is not across the board. A podcast that I listen to has its website on Dreamhost shared hosting, and that site is up.

yeah my entire hosting account is up and my uptime robot monitoring reports no recent outages.

How (over)subscribed are their servers is an information I'd like to know

Busy dd_rescue'ing the one hard drive it has. (joke)

It's taking a while since it's a mechanical hard drive.