Very strong emotions on this subject.
I stick by my guns. We as individuals have to learn to deal with all kinds of situations no matter how difficult they are. Life can throw some devastating curve balls.
What's probably missed in from my opinion is that I will ensure my kids safety first and foremost but if I feel it could be a learning experience then I would prefer to see my children handle it. If I step in, then I will be a crutch to them. Maybe the first several times are fine, but I won't always be around to fight their battles. Nor should I.
Can't speak for
@Shadow Wolf, but in my case it's more a nod to my primary school teaching background, my psychology training, and my experience as a parent.
Not suggesting that makes me an 'expert' on this, just giving some information on my reasoning.
Trial by fire works great AFTER someone has been prepared to cope with it. It reinforces a belief in their own strength.
Trial by fire can cause great damage if performed BEFORE someone has been prepared to cope with it. It becomes a mental barrier, a scar.
I'm simplifying greatly, but I am convinced of this. Some kids would be ready/able to cope with such trials very early, and this would speak to their home life, their genetics, etc. Some would not be ready.
Kids that lack confidence, etc, tend to more often become the targets of bullies, who are ultimately seeking to reinforce their own sense of power, often based on an underlying powerlessness against some other force in their lives (parents being a common example).
I like letting my kids fall. Helicopter parents (hovering around) do a massive amount of damage to their own children, in my opinion. But targeted and repetitive bullying isn't a 'normal' life experience.
If I can draw an analogy, my daughter is playing basketball. Playing against some stronger and more aggressive kids is good for her, I think. But she is 7. There is a limit. Were I to throw her in an under 15's game, all she is going to learn is that basketball is no fun, and it's easy to get badly hurt. The 'trials' need to be ones your children have a legitimate chance of learning positive lessons from. We all learn from all things. But 'learning' isn't inherently positive.