Lawns that suffer from poor drainage are usually in a poor state of repair. Poor drainage in lawns can be partly due to compacted soil, or by the lawn being laid onto a heavy/clay soil.
This oxygen is required for these cells to metabolize - without which the cells, and later the roots themselves, will die.
Simply put, the health of your lawn can severely suffer in waterlogged conditions allowing moss and weeds to take a foot hold.
In extreme or prolonged conditions the moss and weeds will once again out-compete the turf.