Doesn't "everything Plato said was stupid" count as philosophical progress since Plato ?
Maybe, but that is really only the first step and the easy one. The trick is the second step which I don’t think has been written down yet. That for me would be a sign of progress.
I picked Plato because I believe he is credited as first writing down a western philosophy
Only if the things Plato said were actually stupid. They were not.