Its one of the facts of life that metal camera bodies are much more susceptible to damge than polycarbonate ones, which are pretty resilient to knocks, scrapes and bangs.
There are some special vulnerabilities in my experience. I have dinged the top of an M3 while it was wearing a lightmeter. A bang against the meter caused it, in turn, to dent the flat part of the top plate of the camera slightly. It was not a heavy bang. But then again annealed brass is soft.
SLRs are known to be particularly susceptible to damage in the prism cover department. For example one often sees vintage Nikon Fs with non metering prisms where that unit has been dented at the apex of the prism or elsewhere. Same with the old medium format Pentax cameras that are built like 35mm SLRs. Partly to do with the way pros treat their kit I would say - but also a design weakness that has been repeated year in year out till cameras started being made from high end plastic.
Lighter cameras are even more weak in those respects. I had a mint Pentax MX with a lovely 50mm f1.2 lens that I was oh so proud of. I was wearing it over my left shoulder on a shoulder strap when it banged lightly against a door frame as I walked through it. It seemed barely more than a touch but it still left a nasty dent. The old Olympus OM1 etc models are said to be similarly vulnerable.
As an aside, I think that wearing a camera strap over only one shoulder must be a cause of a lot of damage - the camera can swing about as described above and sooner or later it will bang against something or someone. Or it can just slip off the shoulder onto the floor. I have done both.
I have also managed to ding a Leica M4P that was in a cushioned camera case that somehow slid off a low bench onto the ground. Again I would have thought it should not have done any damage - but guess what!!!
So there you are. If there is a way of denting a camera, I have done it. Its just too easy.
A friend was travelling recently when his new Nikon slid off a cafe counter top onto a hard floor in Amsterdam. The camera did not work till he got it home and after having a technician check it out found that the mirror had jammed. He flicked it and it returned to its proper postion. No lasting damage, ding or dent. It was a modern DSLR.
I have learned the hard way. If a camera is on the floor it is unlikely to fall any further. And so this is what I now try to do whenever the need arises. Balancing an expensive M8 or something on a chair is just too risky, even if its in a case.