I had been reading through old posts, and I can across this one.
It has a lot of science behind it, but it is saying that the size of plant won't really a fact the maximum fruit size. It appears, to me, to say that the number of cells in the fruit, is the only thing that really matters, when determining fruit potential. Since we can't actually see the number of cells, I think that this is even more luck, than anything else, but I was wondering your opinions.
The other comment I have, over 100 2000 pounders have been grown, and I am pretty sure they were all in over 500 sq ft. This means people get more lucky ina larger area?
My opinion is that the fruit has a determinant ceiling for weight, and this can't be changed, which is why fruit growth taper late in the season, but I think that the plant size is needed to help the fruit continue to grow until that "ceiling", and not taper out quite so quickly. It also says that there is no proof that giant varieties need giant plants to grow big, but they are better at creating a sink for the growth. This would also implies they need bigger plant, because the bigger the plant, the greater the sink can be. Also, it says that the pumpkin with the best plumbing, no tthat ist solar panels wins the weigh off. While I agree that the plant size doesn't directly create fruit size, the plant does help that plumbing move the energy faster. If you have amazing plumbing, all focused into one sink, it can't do a thing without the water pressure at the other end.
Plants run on photosynthesis, without leaves, they cannot get the energy to cycle through the plant, and grow fruit. With that in mind, it makes more sense that an established plant, even terminated after the fruit starts would be better. If the fruit is 12 feet out, and on a large plant, it already has the potential for its final weight. Then, if you grow the plant until day 15, it hasn't started to be a big sink yet, and will not yet compete with the leaf growth, as long as you have the nutrients. Then termination of growth will create a sink in the fruit, and let it take over. You would then have bigger newer growth, that would let you keep that pumpkin moving towards its "ceiling", for a longer time.
So I think that the plant size, at pollination, is not a definition, but more of guidelines, for the fruit weight, and will be greatly influenced by how well the plant continues to push the fruit later in the season. This is just my 2 cents. I would love it if someone else could chime in with their opinion on the subject.