Teacup is derivative of static precision rifle shooting with a bladed stance, supporting the firearm with the support arm elbow straight down and typically impinging upon the hip for support. Shooting a pistol this way, the support arm becomes a shelf upon which the firing hand rests - hence teacup on a saucer. This was a relatively productive stance used for static precision competition on square ranges for a long time. The split Weaver Stance incorporated this tea-cup and saucer hold for combat/LE and defensive applications, retaining the bladed stance to present as thin of target as possible with the supporting near arm partially shielding the vitals.
The advent of body armor and the realization that the heavily bladed stance is tactically disadvantaged for movement and visibility promoted a more forward pointing hip and chest orientation, and lead to the isosceles grip and more even stance we teach today.
Understanding the application of the teacup and saucer technique isn’t a bad thing. Training regularly for defensive or offensive application with the teacup and saucer technique as primary and singular technique is a bad thing.
Without question, teacup brings a significant disadvantage to recoil management and recovery, BARELY improved over single hand shooting. Its advantage is precision, with the disadvantage of limited mobility and poor recoil management.
But certain specific applications dictate specific adaptations. Boxers, Muay Thai kick boxers, wrestlers, and mma fighters all nearly squarely face their opponents, whereas TKD and Karate point fighters are nearly fully bladed to one another and opponents’ hips and chests are nearly facing opposite directions, perpendicular to their line of fight. Shooting a 2 handed precision game, a heavily bladed position and corresponding teacup support position might be an advantage, for any movement game, a more squared position is advantaged, whereas for one handed precision games, the OPPOSITE bladed stance is typically advantaged… tools for tasks…
But for the handgun generalist, shooting 2 handed, teacup and saucer is a novelty, not a method.