Board Thread:Theories and Speculation/@comment-34661853-20181111160651/@comment-32685487-20190107235821

They didn't keep it.. why? because they did not have the dna in them. The KinGin bros can go into V2 mode because they ate Kurama's flesh to survive and somehow it became part of them and that is still dna. You need not just the chakra, but the dna and the compatibility to do it. Others have eaten TB flesh and died, proving you need to be genetically capable of integrating the new dna into you.