[0]: magazine article by the author of GGPO [pdf] https://drive.google.com/file/d/1cV0fY8e_SC1hIFF5E1rT8XRVRzP...
It is incredibly jarring to assume a remote player takes an action, display them taking that action, then roll back when you realize they didn't. From your local perspective, it looks like they blocked for a few frames, which makes you assume they're going to block, then they flash back to being defenseless, and your attack weirdly goes through even though you anticipated that it did not.
Even if you can get your fancy neural net to figure out that the enemy is likely to block you - which is a feat worth writing some papers about - you're still going to be wrong about the frame on which they do it. Was their reaction time 160ms? 176ms? 182ms?
If you're right about the action they take and wrong about the frame, that's going to cause each action in the game to have weird timing. You anticipate a block, then it doesn't come so you roll it back, then wait, it actually has come it was just late! The remote player flays around like they don't know what the hell they're doing, and it's not clear to you when you land your hit whether the timer started from when they first telegraphed their block or when the glitch occurred. Your punch appears to land at random.
And blocking is an insignificant action - what if you're playing something like DayZ and the neural net decides that some random other neutral player is likely to try to attack you, say because they happened to mouse over you qucikly.
It looks like they just shot you for a few frames, but weirdly your health goes down and springs back up again, but you're not going to figure out it is the netcode playing tricks on you. Instead you unload your magazine at the other player that's clearly trying to kill you.
And since you are actually shooting now, of course they're going to return fire. Your prediction algorithm just caused two peaceful players to fight to the death.
Just because the algorithm is simple doesn't mean it's possible to do better.
I didn't mean disappointment that the tech hadn't advanced, I meant that my expectations were set really high by the grandparent comment ("Neural networks? In 2006? Surely not! But it must be something really fancy, judging by all these flowcharts!" [0]) and by how they kept hyping up the "prediction algorithm" for half the article, when it's just
1. take the data you already had
2. (there is no step 2)
[0]: https://drive.google.com/file/d/1cV0fY8e_SC1hIFF5E1rT8XRVRzP...
Think about the time scale under which this prediction is made: 60Hz. Even the best players do not change input at nearly that rate. So it's clear that the current value is going to be the best estimate for the next value. That realization doesn't even begin to solve the problem though!
Predicting right is only important in short bursts at critical moments, and it’s also the hardest to predict and less forgiving moments, so I’d assume being conservative is the more cost effective and pragmatic choice.