I suspect the largest D1 premium comes on JFK-LAX where it's written into a lot of actors union contracts that they fly J. If you have to get an actor from one coast to the other, you might not like the cost, but you have no choice but to pay it.
JFK-SEA might suffer a bit because Amazon's policy is that everyone flies Y.
As a pre-COVID regular on JFK-SEA, the last time I was looking at these flights, there were 1-2 daily D1 flights and 2-3 daily flights as F. The problem is that Eastbound, the flight is too short to justify D1 and the redeye (which you want the 75S for and pay a premium for) was regular F on a 739 or 752. Westbound, the flight was long enough, but the timing of the D1 flight either did not fit within a business traveler's schedule or was so exorbitantly priced, that even on OPM, one could not justify the cost. Also, depending on your location in NYC, going to LGA or EWR, you would leave your hotel, take a flight with a quick connection through MSP or DTW and arrive in SEA at the same time as if you took the nonstop since you saved time not making the trek to JFK. Those flights were running about $400 one way in early 2020. The nonstop would often be $1600 or $2800. For those reasons, I never took one D1 JFK-SEA flight.