We routinely use this information in a dashboard to help us see replicaset changes only without needing the entirety of months of data

Running db.adminCommand({getLog: "rs"}) on 4.4 returns an error as there is no RamLog for replicaset information. 

The new JSON format started in 4.4, but did not bring along with it the replicaset log. While documentation about the getLog did change for 4.2, the "breaking changes" list did not include any information that would suggest an exception to be thrown when people requesting this, (assuming they had previously been requesting it, as we do)