I understand what you're saying, and I am not arguing with it, exactly. I am just pointing out some other aspects of it.
Here's something else to think about:
Let's assume your 7-player tourney, which means it's a 3-rounder. The top seed has a bye, so he plays 2 matches if he makes the finals. The non-bye players play 3 matches if they make the finals.
Now, the bye player, IF he wins the tourney, gains LESS than the non-bye player, because he only gets 2 match wins instead of 3. And if he LOSES in the finals his rating drops MORE than it would if he played all 3 rds, because 1-1 is a worse percentage than 2-1.
This fact has been pointed out in the past by high-rated players who feel that it's not fair to them that they have byes so often...
In other words, there's many correct ways of looking at the same situation. As it stands now, we have a mixture: some random, some rated, some ss, some ps. I think this is the best we can do.