havent played much MP so didnt know that
fair enough
i mean it's not completely out of the question for a mamluks and ottomans to co-exist but it's usually much better to kill the other
mamluks have an incentive to declare as soon as they can because they start a bit stronger, which means ottomans, instead of expanding into byzantium, need to focus on preparing for a war with mamluks as soon as possible which often involves taking the countries bordering them, and after that ottomans then have an incentive themselves to declare as soon as possible because they start out with a 6/5/6 ruler and thus will get military techs and ideas before mamlukes
essentially their whole starting situation is made in a way that it encourages a very early war to make the other unable to contest you in the future, after which you essentially just cant resist in any meaningful way and might as well leave the game since once you lose another war, chances are you're almost guaranteed to lose the next one
to be fair, though, to argue in your favour, if mamluks or ottomans are picked, picking the other country is usually interpreted as "I want a 1v1 at game start", which is why it's usually not considered a fun combo for games where you want everyone playing to be able to continue in future sessions. it's certainly possible to talk before that and just work out a border deal or even an alliance and avoid the 1444 deathwar altogether, just that it doesnt happen due to how it's often interpreted in mp games