Doing so will give them 60-90 minutes of extra air, the passengers' masks don't last that long.
On the other hand, the ability to shut down a system that has failed can save everyone on board.
There are approximately 40,000,000 flights each year. Almost all occur without incident. In the entire 120-year history of aviation, only a few accidents have resulted from the pilot intentionally crashing the plane.
At the end of the day, there are so many other ways for the pilots to down an airliner and kill everyone, they are ultimately the only people you can’t practically have the system distrust. The only thing you can do is the rule to always have two people in the cockpit but it doesn’t always help.
Ultimately the pilots have to be able to turn anything off that might malfunction.
Also even if you (try to) take capabilities away they are by definition quite smart people and could probably figure a way round if they really wanted to.
Ultimately the pilots have to be able to turn anything off that might malfunction.
If that extra pressure goes away for whatever reason, people are handed oxygen masks and tanks to help them stay alive. What the GP comment says is that the plane may have been depressurized at one point at high altitude. The pilot’s oxygen mask is usually designed to last longer than any of the other passengers’s masks do. So it’s not entirely implausible that the pilot can still guide the plane into controlled descent, while all the other passengers may have already passed out due to lack of oxygen.
Not most people. Nobody can breath if the altitude is high enough. There are some individual variability in how high is too high. That is of interest if you go mountaineering, but not really in a situation where an aircraft rapidly decompresses at the altitude MH370 was speculated to be flying at.
Read generously, they're talking about with supplemental oxygen. At 35k feet, even with pure oxygen, many people will not be able to breathe and most will not be able to comfortably. (Above 40k feet, supplemental oxygen no longer works--everybody needs pressurised oxygen.)
(Obviously nobody can breathe above the Armstrong limit, but that isn't relevant with a commercial airliner.)
That's why they tell you in safety briefings to always put your own mask on before helping others.