Quite common in Asia that there are no self-service check-in machines. A lot of destinations in Asia require Visa which will need to be verified by the airline somehow. Makes it a bit tricky. Changi is currently studying the possiblities.

But, you could use OLCI even you dont have a printer. The printout is not required. SQ has separte CI-counters for passengers which used OLCI with or without baggage.