"By cushioning that sudden pressure spike, a lot of rear brake lock up's can be minimized."


There is no mechanical basis for a "brake pressure spike", unless the driver releases foot pressure during application to create one, or one has a cold temp grippy brake compound that loses grip quickly after initial brake hit, creating a brake grip spike, which would seem to be a rather dangerous choice.
Actually, the rear brakes are most useful/effective (unless aero rear lift is present) upon initial application, and fairly quickly diminishes as weight transfers forward, front suspension compresses, and whatever rear downforce is at play goes away as speed lowers. A rear pressure delay seems to be the opposite of what is needed for maximum braking.
Actually, one of the small advantages of rear disc over drums is, discs apply braking force and respond mechanically faster.

Based on above, my road racing instructors promoted/taught during on track straight line braking the need for being very aggressive initially with braking and gently rolling off brakes as car slowed and as any turning began.
Which somehow intuitively seems wrong as "smoothness" is often the holy grail in HP driving, but not for straight-line braking.
Usually, front onset brake lockup was preferred, and rear initial lockup was due to improper balance issues for any number of reasons

Your NASCAR Team experience and the information you missed from your driving instructors is showing, but they can't fill a cup that is already full. While some of the information in your post is accurate, your initial statement is short sighted and is missing the point. Reference this quote from the manufacturer.
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"Lock Resistant Brake System (LBS)

The LBS was originally developed for the professional race teams in NASCAR to prevent a loose or over steer condition under heavy loads. It assures the front tires slip first by dampening the pressure to the rear brakes. With LBS the rear tires will accept nearly twice as much braking force without locking up.

The LBS installs easily in the rear brake line and utilizes a unique dampening valve that acts as a shock absorber to sense and dampen the sharp spike in-line pressure when the brakes are applied suddenly.

The LBS improves the brake performance on any race car or truck. The LRP LBS doesn't reduce rear brake pressure, it dampens and delays it. It prevents rear brake lock-up without degrading rear brake performance and overloading the front brakes."