Again with the straw man argument...
I don't think anybody has said, "Hey, YOU! You over there! Don't even think about helping, you will only muck things up!"
What some of us have said is that before we will act, there are some things we will probably consider. (Of course, some situations will not allow much time for reflection, but what are the odds the scenario will start immediately under our noses?)
Those considerations include likelihood of success; likelihood of harms to others; likelihood of harms to our own.
I mentioned that I have pretty good abilities, but would still have to consider some factors. This was not to say that less trained people should do nothing, but to say that I could easily see why they would be hesitant.
This whole issue of trusting others to be able to do stuff is something you have made up, IE a StrawMan.