Fezzik wrote: "The argument that the best player in correspondence isn't a titled player has nothing to do with my statement that a titled player will never be U1600 in correspondence unless they time out in all their games, and a true U1400 OTB player can never be +2200 in correspondence. Generally, the avid amateur, rated 1800-2200 OTB, have been the ones to do the best in correspondence chess before the age of computer. This seems to be the threshhold of understanding that benefits chess research. I challenge anyone to find an OTB player rated +2200 who is U1600 and does not lose almost all of his games due to time outs. I also challenge anyone to find a true U1400 OTB player who made CC master or above before the computer age."
The fallacy of overly specific demands that ignore the general issue. Fact is, a race car that can rocket boost off the start line, even if the rocket only lasts a few seconds and the car is slightly slower than the oppenent when running only on the engine, is still going to have a large advantage.
In the same sense, an average 1500 player that uses databases and books and engines to play a 'perfect' opening and have an ideal pawn and piece structue is going to still have an advantage over an 1800-1900 player who uses only his mind, even if the average player stops using his resources in the middle game. Because as every chess player should know, the better your pieces are set up initially, the easier it will be to organize attacks and defend your own army.
I can only speak from my own experience, but my chess.com rating is about 600 points higher than my current OTB rating (which has dropped about 200 points over the years). I don't use books or engines, but I do make extensive use of the analysis board. I only play 3 day games, and only have about 3 or 4 going at any one time. I put the higher rating down to lack of pressure. No time pressure, nobody standing around watching the game, and the ability to leave the games and come back later for a fresh look.