I haven't been saying 2700 vs 1300 here actually, I'm just saying theoretically why it makes sense a player can have an expected score of 100% even if the rating system will always give some very small decimal just above zero.
As for "unforced errors" I think we need more specific terminology. When a 1300 makes an error it means they lost a rook. When a 2000 player makes an error they lost a tempo. When a 2700 player makes an error...
And also "unforced." Carlsen plays 20 "best" moves in a row and even if the position is equal his opponent can be pressured into a mistake. Is that unforced? Would Nakamura make the same "unforced" error against a 1300?
"The rating system is an estimate based on incomplete information."
"I'm saying in reality, if we knew everything, we could see there are units of information that let you play correctly in specific situations. If you have enough units, you play correctly in all the situations a 1300 can generate."
And this seems to just be a baseless assumption. It's not unreasonable to say that what we consider covering all the units is really just our inability to understand what thousands of games is really like, and the kinds of odd things that can happen with so many. I can't really grasp it either, but I don't pretend I can. You can't just dismiss that just because we casually observe that 2700s make very few unforced errors. How many games do we look at to base our decision? Maybe dozens? That's not close to enough. When we see hundreds of quality moves we get absorbed in that. But we're not talking hundreds of moves. We're talking about hundreds of thousands of moves. The 1300 only needs a tiny percentage of opportunities to win a tiny percentage of the time.