Alright first off we are obviously discussing a fictional book/movie. We can all agree on that. Second the dinosaurs being cloned could not grow to that size because the oxygen today is much thinner than it was at that time, which allowed for their massive growth. That being said you trying to use physics, and thermodynamics doesn't calculate. We are talking about biology. A blue whale adds sometimes over 200 pounds a day as it grows, and reaches full size in most cases around the 20 year mark. That's 4 times the weight being added that you cited as going against physics. Now the diet is different, it's not plant based. Still that doesn't matter. Animals can grow very quickly from plant based food. A bull will go from 50 pounds to over 2000 pounds in a few years while a human by comparison isn't even remotely close to that kind of growth. A bull isn't capable of reaching 100 tons, but another plant eating animal that has evolved to reach that size would absolutely put on the amount of weight you cited, in the distant past. Today? No because of the oxygen, and different climate.
I will also add that although it is absolutely impossible with current technology to bring back dinosaurs, in this fictional world there was major genetic manipulation. Combining frog dna for example. If other alterations were done to increase the dinosaurs growth rate by sacrificing it's life span, and if they were exposed to growth hormones then it is conceivable albeit not very likely that there may be a chance an animal like this could reach incredible sizes in 15 years.
First, biology doesn't get to ignore physics. It still matters. Thermodynamics absolutely plays a part in digestion. It's conservation of mass and energy—and none of it is lossless. Blue whales eat between 2,000 and 8,000 pounds of krill daily to gain that 200 pounds, for instance.
I also think you're missing my point. It's not that these creatures couldn't have existed, it's that they couldn't have been hatched within the past five years, the time period stated in-universe.
That's the problem with the conservation of mass.
My point about plant matter was that the loss of energy and mass from consumption plays a big part, as the plant matter they're eating offers less than animal matter (lots of fats and proteins, for instance). A bull takes fifteen-twenty months to grow to full size, and eats about 25 pounds of hay per day to reach its full average weight of 2,000 pounds. Round that down to 2,000 pounds in a year as a best case scenario, and you still have fifty years of growth to reach the size of a brachiosaurus. Even at double or triple the rate of growth, which seems unlikely, you still have well over a decade necessary to grow to full size.
And yeah, I'm well aware about the oxygen content of the atmosphere's importance; it's another reason why I like the theory that Hammond wasn't making actual dinosaurs, but things that were different altogether. The whole amber-ed mosquitoes thing was just a fiction he sold his investors, and he made these things out of whole cloth.
It's ignored mostly by the movie canon, which acknowledges the differences with the dinosaurs in Jurassic World (which I appreciated). But the books never dealt with this sort of thing.
Personally, I think you and I are in violent agreement. Mostly, I just want to live in a world with megafauna so I can ride a ground sloth to the grocery store, and I'm grumpy that it isn't possible.