As far as I'm concerned, that assumption is nonsense.
Would Guilliaume Zuili's work be "improved" by availing himself of the characteristics of a larger format film?
IMO, absolutely not. In fact I think a step up in format might just ruin it.
The choices we make as artists using photography; of lens, film, format, lighting, filters ... simply imparts certain characteristics on the prints we are trying to get to.
None of the characteristics that our tools or materials impart on a print are intrinsically better or worse than their alternatives.