Isn’t it the case that the RG unis have the highest grade requirements for most subjects. That means they are more competitive and difficult to get into. Therefore students are working with an able cohort.
When employers look at where applicants went to uni, attendance at a RG Uni is a useful indication that they were academically bright. You could tell that too from A Level results.
Is it snobby to want to recruit academically bright people or the brightest? Not really. Being academically bright might not be the most vital thing for some jobs but for lots it will be. So many firms that hire graduates for their training schemes with big salaries and well paid salaries after qualifying in their field want the brightest students. It’s not un reasonable to look for students with the best GCSE and A Level results, attendance at top universities in terms of difficulty of admission and degree type and class.
Employers have to distinguish between candidates. They have to sift when hundreds apply for a role. They cannot interview everyone. It’s not the case that all candidates are academically equal and university attended is one indication of their level.
So whether the actual experience of studying at a RG is different or superior might be tricky to tell, but you can say you’re likely to amongst a similar cohort. Perhaps it’s the equivalent to going to a grammar school or selective private school. Being with a particular able cohort might make a different learning experience. It might allow higher standards to be attained. It might attract a better quality of staff (or not).
And as always, people like to point out that in certain vocational areas,RG unis are not the best. That’s fine. For people who know they want to go down a particular path, attending whatever’s best for that seems sensible. For the many who don’t know exactly what they want to do or who are looking at non-vocational degrees, attending a highly regarded uni seems a good idea if you can get a place. Clearly not everyone can, in the same way, not everyone gets 9s at GCSE or A stars at A Level.