I know that GPON is shared; but as you say it's rarely the 'weak link'. Regardless, even if it was, it's much more likely that the downstream would be saturated

I know that GPON is shared; but as you say it's rarely the 'weak link'. Regardless, even if it was, it's much more likely that the downstream would be saturated on the gpon level vs the upstream - consumer ISPs are much more downstream heavy than upstream heavy, so I have no idea what the parent post means when he says that its hard to saturated gigabit uplink on consumer connections. It's the opposite if anything.