Unfortunately, the transition from analog broadcasting to digital robbed many households of access to stations that could be received before the format switch. Analog signals were easily receivable with indoor/outdoor antennas, but digital signals aren't. If you're lucky to live in the right city, and in the right location, you can pick up all your broadcast local stations. I can only pick up 2 stations now with an antenna, only one of them is a network affiliate. In the old days, I got 15 stations-3 more when it rained.
So cable is a must for some if you desire all your local network affiliates.