You already know, the contractor who responds first wins the job. When you're on a roof or behind a mower, you're not answering the phone - and by the time you call back, they've already booked with someone else.
Homeowners research contractors at night and on weekends. If no one's there to respond, they move on to the next name on their list. You'll never even know they were interested.
Between quotes, jobs, and running the crew, following up with every lead is impossible. Good prospects get forgotten, and money gets left on the table.