And lowkey everything Tony wanted as a child.AJ is the manifestation of everything Tony hates about himself. once AJ said he was depressed that lit the fuse.
A father who gives (more of a) shyt, a mother who isn't abusive, a sister who isn't manipulative. None of them were perfect but Melfi pointed out a few times that the things Tony complains about wrt AJ are things he missed out on as a kid. AJ is allowed to show thr exact same weaknesses Tony had in him (like you said) but has had to hide/suppress for all of his life.