Now that I agree with. The side discussion on this thread (is talent the same as consistency) is just that, a sideshow. It has, as you have pointed out, no relevance to quitting.
What, it seems, might have relevance is how good a player once was. There seems to be a line of thought that players who had been really good players might want to quit when their game left them, whilst hackers like you and me might carry on happily, not knowing what we were missing. It sounds a sensible argument. I'm not buying it, though, and think it takes a sizeable dose of arrogance to give up a game (or not enjoy a game you once did) simply because you are no longer as good. If golf (or any sport) is just about being good it seems to me that the player who feels that is missing out on much of what makes golf a great sport (and I don't think golf is unique in this). No sport is just (or even mostly) about performance.
Last year on holiday in Elie I was fortunate enough to play in a group immediately in front of another group, consisting of four old men, each a mid-teens handicapper. One of them was of note because he was a five times Open Champion. This man, who had once conquered the great links courses and proved himself one of the worlds leading golfers of his generation was happy to enjoy being out on the links even if he wasn't breaking 80 on what is, in reality a short and easy course. If Peter Thompson isn't ready to quit it strikes me as perverse that some lesser (albeit decent) golfers should quit for that reason. Perhaps they need to understand what Thompson understands, that golf is as much about the cameraderie, the challenge and the sport as it is about pure mechanics and numbers. Perhaps they would enjoy olf even more if they understood that.