The manipulation of qubits during computation uses gates that can modify the coefficients of a superposition, not just flip the state. This vastly increases the information density of a quantum computation.
The gates operate on qubits to change their quantum state. When the qubits are measured, their quantum state collapses and the computation is over.
Quantum computing then is about processing information with the quantum state and extracting the final form of that information through the measurements.