Why redirect bass
Subwoofers can be placed where low frequencies behave best in the room, while screen and surround speakers can be placed where imaging and coverage are best.
The crossover is a transition zone
Both the speaker and subwoofer contribute around the crossover. Level, phase, delay and slope determine whether they sum smoothly.
Large speakers can still be crossed over
Even a physically large LCR may benefit from bass management because room modes and headroom are better handled by a dedicated multi-sub system.
80 Hz is not a law
The correct crossover depends on the actual in-room response, distortion, placement and headroom of the speaker and subwoofer system.
Measure every seat
A crossover that looks good at one microphone position can still create problems across a seating row. Multi-seat optimisation matters.
Apply the principle to your room.
Send the room dimensions, seating plan and proposed system.