The gear sizes for regular roadies are designed for athletic cyclists riding at an athletic pace. Professional riders use pretty much the same range of gears.
People who are not athletes , or dont want to ride all out the whole time need lower gears, and road triples (like the Shimano 105 triple) are about right for these people without luggage in steep terrain.
If you are dragging a full camping load all day up mountains, steep hills and dirt tracks, and you dont want to work at an athletic pace, you need much lower gears. Most tourists these days would recomend a 24" gear as the lowest. You have to sacrifice some of the range at the top end, but these riders dont feel the need to pedal hard downhill. Hills are for rolling down.
I have a road triple on my touring bike. I have used the 50/13 once, with a strong gale behind me. I changed the 30 for a 26 to cope with steep hills, but the system doesnt work smoothly, so I need to change the crankset to a smaller geared one.
Often big mountains dont have such steep gradient. In the UK, we have many short hills which are far steeper than any alpine pass.