Ottomans don't have as many food issues, especially with military schools producing free units passively nonstop. That's one reason they match up well against food-reliant civs like Chinese.

China is one of the most difficult civilizations to play, making it hard to squeeze maximal value from all bonuses. Ottomans just invest into military schools, and once up, they passively generate value nonstop. That's an enormous advantage.

Chinese players sometimes try double stable horsemen. You can get more ponies out than Ottomans, but it's quality over quantity — Sapahi are better. And you need to have a way to deal with the imams.

China has insane age-up speed. You can start your age-up when the Ottoman is halfway through and still finish first.

Janissaries take a while to mass in Castle Age — through the vizier point, military schools, or manual production. Early on, cavalry can get plenty of advantage. But later, once there are enough Janissaries, cavalry cannot be present in a fight and are forced into raiding.