Is this because journal editors like to see their own lines of research expanded on? (Incentive problem?) Or harder to referee novel papers? (Time and attention problem?)

sad but very true

Can you think of a low impact paper that later turned out to be too novel to get published in a high impact journal at the time? How often do you think this happens? I for one don't see this a lot. What I see more often are people that think there work is super novel, and either it's not, or they don't have enough evidence and don't know the field well enough to know that they are wrong.