The "/damage" command exclusively permits selectors targeting a single entity.

The "/damage" command is restricted to damaging only one entity per command, which presents challenges when using the "by <entity>" parameter. This limitation necessitates additional, potentially unnecessary logic when attempting to damage multiple entities with the same source. If there were no such restriction, a simple execute command targeting the entity following "by" could suffice, using "@s" afterward. Presently, resorting to tagging becomes necessary to achieve similar outcomes. This issue is connected to MC-121807.