Ironically, though it is against the law to shoot songbirds, it is not illegal to destroy their nests. Thus mowing does nothing to remove pollen. Mowing eliminates a good filter that removes dust and other particulates which are health hazards that pose problems for the entire population. Cutting removes good food and cover for wildlife. Mowing maintains the landscape at weed level.
Annual weeds germinate and thrive in disturbed soil.
Frequent mowing retards the growth of perennial native flowers and prevents their seeding.