No, I cannot put with the BS. I am the only one here who is talking facts and not some subjective nonsense.
In saying the jigsaw statement, I could totally spot that you believed Lexus takes three different chassis and from three different parts and then screws them together. Why? Because you read it somewhere. I am sure if the internet said that, it must be true.
That is not the truth. I said above, RCF is a UNIBODY construction. Technically, a UNIBODY construction from the ground up is built as one single unit. It was designed taking three different existing chassis, but the construction itself of the final car is using one single unibody construction just like any other chassis with the addition of added reinforcements. the net effect should be the same. It is impossible you could have spotted any driving characteristics because it was designed off three different chassis parts because it it is all one single unit.
I would also finally answer your question as to why Lexus added so much rigidity to the chassis? Simply because it was so that the roof could be chopped off and no reinforcements would need to be added to strength the chassis.
Also, no one said, Lexus should chop an RCF chassis to make a Supra chassis. It makes no sense. It is fine as it is with the existing BMW chassis. I mentioned above, it was because Supra always had been a 2 + 2 with some practicality. Only then, it can be a plausible option to re-use the existing RCF chassis if it had a longer wheelbase and more practical car.