SERVER-33061 added a call to reject command if it does not have snapshot read concern implementation. https://github.com/mongodb/mongo/blob/r3.7.3/src/mongo/s/commands/strategy.cpp#L225
However the supportsReadConcern on cluster commands for distinct, count, group need an overwrite to support readConcern majority to have the same behavior as before.
Eventually this check may become redundant as the cluster commands should support same readConcerns as mongod counterparts.