It's possible to make a much lighter steel frame than a Surly.

...But you don't see many like that any more. Some bikes that are more like that, like Soma, get a rep/rap for being a bit wimpy.

One part of the MTB origin story is that Tom Ritchey jumped on the bandwagon early because he realized he could buy straight gauge tubing in bulk, miter it with a hole saw and zap it together, for a fraction of what it cost to get branded tubing and lugs.