I mean, I'm sat here in my living room, place was built 1798 (relatively modern), near as damnit everything is original. Stone floors. Stone fireplaces. Stone walls. Lath and plaster ceilings. Lime plaster.
They knew what they were doing, this shit is built to last.
These days, they also know what they're doing, but a house has a shelf life of 30 years, so you can tear it down later, not feel bad, and stimulate the construction industry. In theory. I. Practice people live in leaky shoeboxes made of twigs, paper and tar.
Finally, the insurance industry drives this. Ever try insuring a 100 year old slate roof in America? Good luck with that. They'll insist you rip it off and replace it with tar shingles, because no roof more than 20 years old can be any good.
My other property has a 13th century stone roof (limestone, stacked), and it's barely been maintained and is in perfect nick after 600+ years.
A.) Snow doesn't come off of shingles worth a damn unless you have a wicked pitch on your roof. So you have to get up and shovel off the roof, or risk icedams, leaks, and potentially the whole roof collapsing if you have really heavy snowfall.
B.) Shingles only last about 20-30 years. Steel roofing lasts a lifetime. You might have to repaint it once in a great while.
I'm unclear what point ventilation or insulation in the attic would have to do with ice dams... In my experience, it's caused by snow that doesn't get removed, which then melts, seeps down to the roof, and refreezes, with the texture of the shingles providing a greater surface area to freeze against.
All things being equal, it's nice to have a steel roof that will warm up on a sunny day and have all the snow slide off.
The snow melts because of heat coming from the inside the house. [1]
So if you keep your roof cold through insulation and ventilation, you don't need to remove the snow (as long as the roof can handle it structurally)
[1]: http://www.erdc.usace.army.mil/Portals/55/docs/CEERD-RV/CEER... [pdf]
https://en.wikipedia.org/wiki/Planned_obsolescence