Is it true that it is required to submit hotel confirmation letter?

my brother holding indo passport, taking china tour from Singapore. Is it true that it is required to submit hotel confirmation letter? I inquire singapore tour agent, they do not provide it. They can only provide package iteneary with hotel information. Isn't this already the proof? how should he proceed to apply, everything already confirmed, package tour already paid.
by the way, he is applying from indonesia.
sorry for the duplicate.