Cleaves and frontal cones are a very elegant way to teach tanks to face bosses away from their friends and keep them that way. Cleaves and frontal cones are very common in ARR, somewhat common in HW, and quite rare in everything beyond. Cleaves and frontal cones dovetailed very nicely with positionals. These mechanics were not vestigial when they were discarded, so it's only natural that bizarre situations like this creep in eventually.

Bring back cleaves, bring back threat.