The advantage is that it pushes the development of technology to road cars, which ultimately is supposed to be one of the main goals of F1. That's why we've got tiny engines and turbos back again this year, with hybrid systems. Sadly, the tighter F1 rules become, the less relevance to road tech we see.
LMP1 has been miles ahead on that front for years. Diesels, hybrids, regular size tyres, fuel economy etc.