The advantage is that they will help you reduce your time spent in analysis. This is one of the best ways to make use of or follow trading signals channels or services. What is your opinion?
My opinion is that those who use signal groups only identify one advantage and that is the one you already mentioned. Other than that nothing else looks positive to me about copying trade. Someone who is sure of profit may not sell his money to other persons because that is what it appears to allow someone copy you off your trade even though you are also gaining or losing separately. My opinion is that most traders make losses likewise those running copy trading channels, what then is the point to copy someone's losses.