I wouldn't mind having fat manning be removed but it's important in a lot of cases. 50% or more of the games we have with Goldfish end up with him being really annoying which is why we started to fat man him out, even though it gets a little extreme sometimes where you guys literally start begging for one more just to fat man him out.
Here's what I think. If a lot of people join in around the same ~5 minutes, the fat man out process will be used. If you get 10 players exactly who are willing to stay for the entire 10man, then you just start it. If like one or two people join after you have 10, just tell them they were too late. But if a lot of people show an interest in playing and join around the same time, then it would be ok to fat man out.
Or alternatively... we have a REAL fat man out. Anyone who is overweight in real life has to be the last picks. Survival of the fittest.