it's not that simple. the new standard is a complete rewrite of the old one. they are not even compatible anymore. things the old standard used to support are not supported in the new standard. that makes any implementation of the new standard incompatible with implementations of the old one. GnuPG simply refused to stop supporting the old standard and decided to fork the standard itself. on the personal drama my interpretation is that it resulted from people backing the new standard being unhappy that GnuPG didn't go along.

my opinion is that rewriting standards like that is the result of design by committee. everyone wants to put their mark on it. designing a new standard is fine, but the new standard should have also received a new name, or it should at least have been acknowledged that the old standard still needs to be supported until enough time has passed that the old standard is no longer in use. (which could take decades if not more if we want to be realistic and consider that encrypted data at rest could linger around pretty much forever unless actively re-encoded.)

(source: i talked to a GnuPG developer)