I have had GHA in my tank but it isn't a problem. I think it isn't a problem because of my yellow tang + coral beauty + wrasse.
However, if I were to take a piece of live rock from my tank and keep it in a different tank with no fish it will grow GHA + other types of algae I never see in my tank.
Point is I think it is always a potential problem, but once your rank is mature, then you can tweak the input of nutrients and the output of waste to control it.
I had a tank running where I had GHA growing on three sides of the tank and I periodically scraped it off as a nutrient export measure. My phosphates and nitrates were the lowest I have ever recorded in a tank (0).
I think there is potential interesting things to grow from everyone's live rock if ever you have a chance to isolate a piece in a separate tank and maintain it long enough.
So, my response to someone with GHA is to keep your tank running and tweak things to see if it reduces your GHA. Scape out what you can, but reduce the input of nutrients that allows GHA to grow. You could also get fish that eat algae.
I would like to hear people's thoughts on whether GHA could ever be totally eliminated. I doubt it. I also have turtle weed that occasionally grows very slowly in one or two spots and also other algae that pop up occasionally, but never last long enough to become a problem.