Most people know that if you don't submit anything in a codeforces round, the round is not rated for you. So if you are taking too long to come up with a solution for problem A, maybe you should not submit anything at all. Should you hate on someone that has this strategy? No! Hate the game, not the player.
In past rounds, I believe that the number of participants in greatly correlated with the difficulty of problem A. Is that the kind of behavior we want to foster? Is it intended that the rating should be a metric of your skill only among the rounds that you want to participate? Or should it be a metric of your skill among all rounds?
So I humbly suggest that if you enter the round, it should be rated for you, even if you don't make any submissions. The registration phase could remain the same, not being definitive, but if you click enter in the round between the let's say the 20 minutes window, starting 10 minutes before the round, the round should be rated for you. And late registrations should be unrated, otherwise this proposal makes no sense, because you would be able to check the problems in an alt account and only register late in the round if you think that you will perform well. Maybe you should also be able to register in the round without it being rated for you, but you need to decide that before.
Let me know your opinions!