Question

What could happen if a receiver tries to control the bursts from the transmitter by delaying sending acknowledgments until it has enough empty buffers?

Answer 1

Delaying the acknowledgements may be interpreted as lost of packets or congestions in the network thus trigger unwanted actions such as retransmissions of packets at the sending side. A better way to fix this problem  would be to use a flow control window as in TCP. Thereby stating explicitly how much data the transmitter should send.