there were disney movies that did have segments in 1940 there was Fantasia its segments included Tocatta and Fugue in D Minor the Nutcracker Suite the Sorcerers Apperentice the Rite of Spring the Pastrol Symphony Dance of the Hours and Night on Bald Mountian and in 1943 there was Saludos Amigos its segments were Lake Titicaca Pedro El Gaucho Goofy and Aquarela do Brasil and in 1945 there was the Three Caballeros its segments were the Cold Blooded Penguin the Flying Gauchito Bala Las Posadas Mexico You Belong to my Heart Donalds Surreal Reverie in 1946 was Make Mine Music its segments included the Martins and the Coys Blue Bayou All the Cats Join in Without You Casey at the Bat Two Silhouttes Peter and the Wolf After Youve Gone Johnnie Fedora and Alice Blue Bonnet and the Whale Who Wanted to Sing at the Met and in 1947 was Fun and Fancy Free its segments were Bongo and Mickey and the Beanstalk and in 1948 was Melody Time its segments were Once Upon a Winter Time Bumble Boogie Johnny Appleseed Little Toot Trees Blame it on the Samba and Pacos Bill and in 1949 was the Adventures of Ichabod and Mr Toad its segments were the Wind in the Willows and the Legend of Sleepy Hollow and in 2000 was Fantasia 2000 which had brand new segments including Beethovens 5th Symphony Pines of Rome Rhapsody in Blue the Steadfast Tin Soldier Carnaval of the Animals the Sorcerers Apperentice which was from the first Fantasia Pomp and Circumstance and Firebird Suit but afterwards there were nomore of them and why did non disney animation companies not do any of their own is it becuase disney was more successful with them than non disney .
Disney is the only animation company to make movies like this.
With the exceptions of Fantasia and Fantasia 2000, the other films are called "clip" films; they string together previously produced animated short films, add some animation here or there to help connect the clips, and then they released it as a feature film. This was mostly done due to the money Disney poured into the war effort instead of creating feature films; between 1942 and 1950, there were no original feature films. This way, Disney could make money while still helping their audience see feature films.
Fantasia and Fantasia 2000 were both original films because they were planned for years ahead of time. Each segment in the films was uniquely made specifically for each film. They're oftentimes considered a completely separate category from the other clip films.