Under this configuration, any one appliance may not exceed the 5mA trip setting of the gfci device. However, several appliances operating together may.
I am not disagreeing with you on this. In my years of experiences, I have never had an issue with GFCI's tripping because of this. I have heard dozens of claims of what causes nescience tripping. I would say 0.1% of claims are truly nescience tripping. The rest on the time, they did thier job. This is providing that the circuit is wired properly.
Do not quote me on this but I do not think that household appliances are allowed a certain current leaking (with the exception of surge protectors). I do not think capacitors are allowed an x amount of leakage. They do in time leak due to age. If a GFCI is tripping, it is 99.9% chance there is a pending problem that should be addressed before it comes a real problem.
Number 1 complaint I get about so called defective GFCI's is, "I plugged my hair dryer in and the GFCI trips. I plug it in a regular outlet and it works fine. The GFCI is broken."
I live in a very wet environment. When installed and used properly, we get many good years of service out of them providing the poor power quality dosen't kill the circuit board first.