The name is well known and been around for a long time. Since its synthetic introduction it was top of the game. Since its readily available & they spend a lot on marketing people can't help but think its the standard in oil excellence. You say synthetic oil and people say Mobil1. At least in North America. Other parts of the world may have their flavor which may be different.
M1 formulations have changed, for good or not as good it is still a great oil. Unfortunately they are pricing themselves out of common Joes pocketbook. When you see Pennzoil, Quaker State, offering their synthetic formulations for $10 less or more Mobil1 seems a little much. For those die hard users, it will be the same choice. Kinda like truck owners always buying a certain brand cuz grandpa and dad did it so must I. Tradition.
For me, I have always known even before BITOG, if I wanted an oil that offered a little better protection, I would choose a sythtetic if I thought the application needed it. After BITOG, I first look at opinion, then look at the UOA's then I go with the best oil, best price, my application. In my truck its PYB, in my car PP.