ThaLoraxI mean, I've been mtn biking for 15 years and had my brakes fail many times. I'd much rather have only the braking power of the front and risk the "screw up" (as you call it) than not be able to stop in time because my bike did nothing but skid over a long distance from using only a rear brake.
Since you brought up the past, 15 years ago I was working in my first bike shop, during that same time I purchased my first bike with suspension. I was riding rigid steel bikes before that.
I also did not say "screw up", I said "one wrong squeeze with the front can easily cause a wreck, while the same isn't necessarily true for the rear."
My ultimate point is, assuming an emergency pull of either the front or rear brake (your opinion vs. mine in this case if you will) there is a much higher likelihood of a crash if your weight is not balanced correctly, your bars are turned, you are on loose terrain/gravel, etc. on your front brake.
Locking up the rear tire will cause a skid, yes I get that. However, it is also easier to correct the skid, or get back in control with loss of rear tire traction than the front, especially when a strong braking force is introduced to the front wheel. Again, from a safety's sake point of view, I'm going with a rear brake.
I'm not assuming anything regarding your skill, or anyone else's for that matter, merely your own opinion on this braking situation. Riding along a gravel road and grabbing the front brake to avoid a dog would probably cause a lot of people to crash, while grabbing the rear brake would at least give them more time to maneuver or correct. That's it.
I had never had to ride out all downhill without a rear brake before, so first time for me there. In hindsight I would have been better off swapping my only functioning rotor to my rear brake for the descent. Loose sand and dust on the hardpacked dirt and rocks was tricky in spots with just the front brake, but nothing extraordinary. I would've been far more comfortable and riding faster if I was just rocking the rear brake.