I have been using PGP and then GnuPG for over 20 years now, and my oldest key is still on MIT server since 1996. (RSA 1024 without subkeys...)
Over the time the keys became pairs of Main and Subkey. In all these years I have not once needed the subkey function. Nor do I know anyone personally who has used it.
I might have read all the "Good Reasons" for why subkeys "should" be used. But none to these reasons applied to me.
E.g. subkeys are great when the encryption key is compromised!!! But my encryption keys have never been compromised. Neither do I know anyone who's keys has.
Or supposedly it is good for organizations where one main key is associated with many encryption keys. I have not seen it. I wonder if such organization exists anywhere in this Universe. From all I have seen, the subkey idea appears to be a case of over-engineering with no or very rare use in real life. Perhaps the idea is just a rationalization of the DSA/elGamal scheme.
In any case, I am working on some software where Subkeys are not utilized. Also, I want my keys to be compatible with RetroShare (a secure p2p IM chat and file exchange, using only single keys without subkeys.)
Does anyone know if there a way to generate keys without subkeys. I am only aware of the option to remove subkeys in the --edit-key menu. I don't know if keys can be generated without them. Is there a way? thank you much for any help to further understand this issue.