For the sake of an index build's commitQuorum, replica set nodes configured with {buildIndexes:false} are not considered data-bearing.
If a commitQuorum includes a voting replica set node that is configured to not build indexes (i.e. buildIndexes: false), the quorum will be unsatisfiable. Therefore, index builds that use the default commitQuorum of 'votingMembers' will fail if there are any of these voting, non-index-building nodes.
The user will either need to specify a different commitQuorum or have an administrator make any buildIndexes:false nodes non-voting.