Back in the day frequent flyers and road warriors used to drive past half a dozen gas stations and ten extra miles to the Shell that accepted Diners Club even though the “low fuel” light had been on all day. We do crazy things for points.
A signup bonus and up to 3 miles per dollar is great. And both earning and burning points are a decent way to keep miles from expiring, buy gas at BP once every 18 months. At the margin it makes BP competitive with Shell (although neither gas is usually cheapest).