One of my opponent say they was “not confident” because of my win against mid-rank dan earlier. Which made me curious and I turned on rank display and then like HOLY COW O_o
I certainly felt I performed well in this game, and maybe it’s one of the bad day for the other person but still holy cow… this is the first time I won against 5d. I’m so very happy. Not knowing your opponent’s rank help a lot people! 
… some moves later …
But testing the other side of the hypotheses, do you have any loses against players much weaker than you where you might have tried to harder to win with something tricky if you knew they were weaker but instead gave up thinking they were an equal?
No I wonder I saw his rank drop… So you were the “culprit” 
Isn’t the trick to play beyond tricks? Be against you or be from you.
The thing is that if you know your opponent is much weaker, even if you are behind by a lot, you can continue to play as long as there remains some hope they will make a game-reversing mistake. For instance if a group is living but doesn’t have clear eyes yet you can still hope to kill it. Whereas if you know your opponent is stronger, you’ll probably want to resign.
Not that I know of. If anything every game felt like a real-life tournament game to me.
I almost only play correspondence games so I don’t have a habit of intentionally playing trick moves: the few time I tried it always ended up badly for me 
(10k) Just wondering the opposite: can’t knowing your opponent’s rank sometimes help? If I know they are weaker, I can get away with tricks, if they are not obvious. If I know they are stronger, I know to be careful not to leave multiple cuttable links and other such weaknesses, and to be careful with committed groups to staying alive: to play more conservatively, hoping to win in the end game.
If you are a stronger player, you can even understand the quality of this posting just by having seen my rank at the beginning.
I’m not sure about the idea that the quality of a post can be predicted by the rank of the poster.
The accuracy of go analysis would be predicted, but TPKs can make high quality posts, and Dans can make awful ones…
Frttgheyjbdc
Not knowing if you are ahead or behind during game may be useful. If you don’t know that you are far behind, you would not resign and would continue to play without panic, then opponent may do error and you would win.
If you would learn how to estimate score during game, you would lose forever such ability. So it may be good idea to never try to learn score estimation.
Possible also to learn to play calmly regardless of situation-- that is one other solution. ^^