Daddy Comments
i'm not fond of it. Despite being old enough to be their dad, that's not what I am and it should be used for their father. In cases of the younger guy looking for a daddy, it implies they're looking for financial support and that's not going to happen. I completely ok with younger/older (I actually prefer younger), just don't use the term daddy.
Daddy is such a loaded term, I prefer to stand clear of it and all its connotations.
It's not a greeting except in very intimate circumstances that usually are biologically based. I enjoy the role play but that's based on seriously engaging with the trust respect freedom and responsibility the bond entails. Its mutual. Dialogic. And genteel. So busting out with it is just inappropriate. It's also imposing and presumptuous.
I have a couple of younger friends who call me Daddy, and I don't mind. I do have an intimate friendship/mentorship with both of them, so it's amusingly appropriate. However, they were both polite enough to make sure I was okay with the moniker. When young men use it as an initial greeting, it puts me off, not because they're calling me old, but because they're implying an intimacy that hasn't been established yet.