I reckon it's marketing BS.
All fuels must meet various standards and realistically almost no engines (if serviced properly!) cause cars to be scrapped in the UK - what gets them is accidents, rust, MoT failure deemed too costly to fix.
I think that some of that is correct, but it only applies to the basic spirit - and as far as I know, no fuel retailer sells their product from the filling station dispensers without first adding in their blend of additives, which get added at that brands dedicated road tanker filling stand at the regional refinery.
Modern car engines would not keep clean enough to continue running within their permitted emissions limits if their were fueled with fuel that did not have an additive package, and that is for us owners the annoying bit because exactly the minimum additive package needs to be is all smoke and mirrors - and that can't be right, there should be quality standards issued to cover different "levels" of additive packages without us needing to know the exact "make up" of these different additive packages - it is the oil and gas industry remember and no one is going to be totally honest about things and what your engine actually benefits from having in its fuel - and so lots of stories and some of us prefer brand A over brand B or brand C - and that excludes the obvious differences that come form using the minimum or above minimum recommended RON version of petrol.