Old School mentality
Whats the purpose of a body lift ? to be able t accommodate bigger tires. What other benefit to you get from it.
Not being able to see past bigger tires must be the New School Mentality.
They can benefit both the Budget and suspension/steering/driveline geometry, help reduce the need to bump stop for tire clearance allowing you to bump stop better for shocks (maximizing shock stroke/reducing lost stroke), allow more room to raise upper shock mounts without getting into the body, help maintain LCOG, provide room to keep muffler and exhaust up out of the way, increase tire clearance without limiting suspension, the little gap between the frame and body makes it easier to keep clean and work on, can be added to an existing suspension lift to increase tire clearance without the need to rework and replace any suspension parts, just depends on the situation.
You can build with or without a BL.
Not everyone wants to cut up their body.
Not everyone likes the looks of flat flares.
Not everyone has the budget to put all the lift into their suspension.
Not everyone wants the change in handling and performance caused by higher lift heights.
Some people choose to use a BL to compliment the suspension.
They are cheap and easy but do not use more than a 1"-1.25" body lift.