It really depends. Airline checkin agents are overcautious as in remote case of you being denied, Airline have to pay the fine. From talking to a checkin agent, if the fault is the agent’s, the fine will be coming from their paycheck (may vary with airlines).
You have three options.
I have done the 2nd one once, as my bio page was intact and I was able to convince that since I am a resident of Singapore, I can use the automated gates and only bio page is needed. Had to sign a waiver absolving them of any responsibility and agreeing to cover financially, in case they were fined.
Credit:stackoverflow.com‘