Pumping while breastfeeding

Ar

If I'm a stay at home mom, do I need to pump while breast feeding? I've had people tell me that my supply will stop or slow down if I don't but my mom and grandma breastfed and never used a pump and their babies still got what they needed?? And my mom had 5 of us. I don't get why I need a pump if I'm always at home with him and he's eating every 2-3 hours...