Short answers, pulled from the story.
Winsor McCay created Gertie the Dinosaur in 1914. This film featured every rock and blade of grass moving with painstaking, frame-by-frame precision. It set a new standard for animation before McCay shifted his approach four years later.
William Hanna and Joseph Barbera adopted limited animation in 1957 because small television screens could not support grand theatrical spectacle. Financial constraints demanded a new approach prioritizing character close-ups and dialogue over fluid movement. This decision allowed them to produce content at a pace that made Saturday morning cartoons possible.
Japan defined anime as a distinct artistic identity by featuring moving mouths, occasional eye blinks, and long shots of detailed backgrounds. This approach leveraged the country's post-World War II economic recovery and the boom in television ownership. The style prioritized emotional resonance and narrative depth over fluid motion.
Syncro-Vox animation emerged in the mid-20th century from Cambria Studios. This technique involved superimposing film of a voice actor's moving lips over a still frame of the character. It represented one of the most inexpensive approaches to animation possible by reducing the need for hand-drawn movement beyond the mouth.
Sony Pictures Animation popularized the modern choppy animation style in the 2018 film Spider-Man: Into the Spider-Verse. This technique utilized computer-generated imagery to create a mixed 2D animation style that appeared less smooth and fluid. The film's success influenced subsequent projects like The Mitchells vs. the Machines and The Bad Guys.