Mintz cutting Disney from Oswald is a far more interesting case when you take a look at the timeline. Let’s quickly look at the series Winkler initially distributed
Felix and Inkwell, 1921: Margaret Winkler picked up both series after Sullivan and Fleischer needed a new distributor for different reasons (Paramount ended their magazine after briefly making it an all cartoon series, Fleischer left Bray to start his own studio). Both had created their own characters beforehand and retained the rights. In 1923-24, Fleischer decided to become his own distributor and formed RED SEAL, taking Inkwell with him. This left Winkler in need for a new novelty cartoon series, so it was good timing for her to see Disney’s ALICE pilot, and she picked up an Alice series. Meanwhile, by 1923 Sullivan and Winkler had issues getting along and by 1925 he signed with Educational, retaining Felix. Winkler immediately hired away Bill Nolan to begin work on a new Krazy Kat series. Sadly, for Winkler/Mintz, Alice and Krazy never reached the heights of the other series, and their departure seemingly taught a lesson to both; control your series and characters
Now, in 1926, Mintz was taking the cartoons to bigger heights, signing with FBO for wider distribution, and was already making arrangements to move Krazy the following season to Paramount, and start a new series with Disney under Universal. At Krazy, in order to better meet deadlines, Bill Nolan had been subcontracting a few to John Terry, and soon Mintz would do the same with slick talkers Ben Harrison and Manny Gould for six Krazies. Their cartoons undercut Nolan, apparently at 900 dollar budgets (I think only about 15K today!) which gave Mintz the idea to give the Krazy to them instead, which happened in spring 1927. This was the other big thing, budgets. Alice and Krazy had smaller budgets than Koko and Felix, and now Krazy’s budget was even smaller, but since the cartoons still delighted the audiences that cared, it didn’t matter.
I’m surprised with this history in mind, Disney didn’t see he was next, that the Oswald contract was be taken elsewhere to be produced on lower budgets while still as entertaining. If Walt did, I don’t think he expected the new animators to be his own animators. Oswald was the first big thing to happen to Winkler since their initial cartoons, so it is very understandable why Mintz would want to ensure that the Oswalds could be produced without issues relating to the team’s ambition, somewhat squashed during the 28-29 season. And who would care, Walt, Ub, weren’t big names in this period. So, out Walt went
Mintz kinda got what he deserved for undercutting Disney and Nolan. Besides Universal deciding to undercut Mintz by producing the Oswalds in house, Paramount didn’t give the Inkwell Imps and Krazy Kats a lot of marketing or attention, which definitely bugged Winkler Productions, who built their series on advertising. Trade pieces imply Mintz almost didn’t sign the 1928-29 contract with Paramount. Beyond this, the cartoons Paramount distributed should’ve been making half the product, both series suffering having to make 26 cartoons per season and lost their ambition, in which that tight $900 budget most definitely hurt the Krazies more than the Imps