SERVER-38356 requested adding guardrails to prevent users from dropping the oplog in standalone mode due to the use of an outdated procedure for resizing the oplog. In versions 4.0 and later, dropping the oplog in standalone mode can cause loss of majority-committed writes. The fix banned dropping the oplog completely for storage engines that support the replSetResizeOplog command on versions 4.0 and later, with the suggested workaround to drop the entire local database in cases where dropping the oplog is necessary, such as restoring a replica set backup to a standalone. This was reverted on 4.0 in SERVER-47558 because it prevented some necessary maintenance procedures. We should consider alternative solutions on 4.0 (and perhaps on later branches), such as adding a force option to the drop command, or banning dropping the oplog only when there is a replica set config.