I like it too. I definitely hear you. For instance, Gilbert and Sullivan... neither of them could have done it alone. Sullivan, in particular, tried, and didn't succeed.
But, I think Seth may be pushing too hard to make his point. I think it's very arguable that at least during the 60's to early 70's, John and Paul were both categorizable as geniuses. As another example, John wrote Imagine without Paul, and it is frequently considered one of the greatest songs of all time. If it was a one-off, that would be one thing, but he also wrote some of the greatest Beatles songs with little input from Paul.
But, I think Seth may be pushing too hard to make his point. I think it's very arguable that at least during the 60's to early 70's, John and Paul were both categorizable as geniuses. As another example, John wrote Imagine without Paul, and it is frequently considered one of the greatest songs of all time. If it was a one-off, that would be one thing, but he also wrote some of the greatest Beatles songs with little input from Paul.