Am involved in admissions at a RG Uni and to be fair the situation at least in my discipline is opaque which is why the very very narrow 'facilitating subjects' measure was introduced. In my discipline we will accept anything in moderation but we need two of the subjects to be 'non-vocational' (another obscure term-of-art). So you could do psychology, philosophy and design tech or maths, chemistry and physics and be in with an equal chance of an offer. But other RG departments teaching the same subject are more picky about the subjects they prefer - although no one is as picky as the original news stories suggest
We do tell students early and often if they contact us to ask other departments what they want before choosing which subjects to take post-AS, but they'd obviously need to know to ask. The current system works to the advantage of students from independent schools who get rather conservative advice at 16 that if they want to do our subject they should take trad subjects to maximise their chances. That is why we specifically don't favour trad subjects when making offers (that and the fact that provided you get good grades we can't see any difference in performance and we've been keeping an eye for a couple of decades now).
I agree with the Guardian story. You don't need a limited range of facilitating subjects to get into Uni, but there is an iceberg underneath which isn't obvious to applicants either, especially if the student does not know what subject he or she wants to study at 16. The fault does not lie purely with schools and it is unrealistic to say state schools should simply get more students to take a narrower range of A Levels to achieve the outcomes the RG Unis allegedly want so the facilitating subjects measure is pretty pointless. The problem also lies with Unis not being clear about what they want at admission too and having diverse goalposts/hoops/etc. And with all due respect to my eminent colleagues I'm not sure a 60pg booklet is quite the succinct guidance teachers helping students make choices post-GCSE or post-AS really hoped for...