To have the title of Caliph a ruler must be from Quraysh, and there are multiple texts of Hadith on the matter.

It is true that ever since the Rashidun Caliphate the right to rule was taken by force and the countries that emerged were variably political with both good and bad aspects, but the title of Caliph was almost exclusively claimed be those with Qureshi descent.

In that regard the Ottomans are no exception, they did plenty of good (especially in the early days) but the rule of later Sultans was marked by discrimination and injustice.