There’s nothing different about the stresses components will experience here in the UK to the Alps
Living in the alps and having spend 4 years in UK let me tell you one thing you are just plain plain wrong.
Here shimano HT II bottom bracket are the panacée, singlespeed is a swearing, and I have yet to see one fox that had the stanchions worn out.
Most of the stress/use put on a component in the UK comes from the mud/weather conditions. Most of the stress/use put on a component here comes from the toughness and the length of the descents.
Then I think it come to the rider. I don’t brake stuff, neither in the alps nor in UK. Put it on the fact that I weight 61kg, or the fact that I have learn to ride in the alps while I was student and hence couldn’t afford to brake/change loads, but generally I do not break stuff. I wouldn’t consider myself slow either (well that was the case before 4 years in UK). However stuff wears out faster due to “normal use in the UK”. Thing like bottom brackets, chains, headset and pads last much longer in the alps than in UK.