Then it will get more puzzled on why he will need to inflate BCD when diving down, only to know that BCD is faulty and he ditch the weight to go up again uncontrollably. This is dangerous boy. Keep your weight, trust me.
LOL, I think there is a grave misunderstanding here. In no way am I trying to insinuate not using a weight belt or any form of ditch-able weight system nor am I suggesting ditching weights with an inflated bcd. I use ditch-able weights myself.
But what I think barebear (based on my inference. but maybe i'm wrong
) is trying to convey and what I was trying to affirm is in the unlikely but still plausible scenario of a failed bcd (not being able to provide any positive buoyancy due to a ruptured/blown out bladder like what my friend had) during the start of the dive at depth, the diver can ditch his minimal 2-6lbs weight to make him less negatively
buoyant (he is still negatively buoyant due to the weight of his full tank and equipments) to assist him in making a slow controlled
ascent to the surface or make any safety/deco stop with minimal
effort. Yes, some might argue that they can ascend effortlessly with all their weights intact. Good for them. But with some divers being grossly overweight with >10lbs weights like what you've seen, I highly doubt they can make a slow controlled ascent with minimal effort from the bottom with a ruptured wing/bladder. Essentially we both agree the best way to avoid all these problems is by carrying as little weight as possible; which is basically the whole idea of a balanced rig. Use minimal ditch-able weight so that in the event that one intentionally or accidentally drops weight, there won't be a sudden steep buoyancy swing to cause an uncontrolled ascent.
Now...if the diver's bcd works fine, malfunctioned (due to a faulty power inflator hose, etc) but still has air in it or is still able to provide lift, please please please for the love of God, do not
ditch your weightbelt. It will definitely lead to a fast uncontrolled ascent like what some have mentioned here or seen when new divers unintentionally dropped their over-weighted belt during dives.
sorry for the wall of text. caffeine rush from my morning coffee.