Hard to give personal (up-)grades based on onsights and for quick ascents

Adam Ondra has given personal grades for hardcore routes for more than ten years, which makes him unique. The dilemma is that he is the best climber in the world especially when it comes to onsight, meaning that he often does not base his personal grades on the best possibly beta. When Ondra onsights a route listed as 8c in the topo and says it felt like 8c also for him, this should not be used as he confirms the 8c, just that he used sequences that felt like 8c for him.

The guys who should confirm grades are the ones who have worked it so much so they have found the very best sequences. If I spend ten sessions on a route I will most likely be able to do 7b+ or 7c, if it is a route that fits me. If Ondra, or another top climber, onsights it and suggests 7c+. The topo producer should not pay so much attention to this as he most probably did not find the best solutions.