Regional Only multi-location gas station chains near you?

[SOUNDMAN5000]

I know Marathon Gas is HUGE ( Over 6,000 stations ) but I remember seeing one the first time about 25 years ago and always thought it was cool Marathon teamed up with STP and had STP on the signs and said STP was in the gas, Made me at least "Think " I was getting more for me money...
I wonder why more gas stations don't market this way?