20 years ago the teaching at my 2 RG universities was by academics (usually professors, often famous not just in their fields but also beyond that), very often we were learning of the very latest cutting edge research. PhD students were teaching assistants in the labs, but didn't lecture.
However even within the RG universities there were differences - at my second (post grad) we were taught by lecturers reading from the books that my previous university's professors had written and lectured to us directly. Really annoying as I could have just read them myself (and in many cases already had) and saved a ton of money and time. I was also slightly shocked in my first professional job to find the difference in quality and thoroughness of technical training, from supposedly the same course, from different universities. Some courses were really technical, thorough, theoretical, and others were a sort of dip into different subjects without ever mastering them, and with the most difficult (read mathematical) parts of the discipline not having being taught at all.
I currently mentor high potential students from under-priviledged backgrounds. We look at courses on a course by course basis, making sure we don't just push them towards the RG. In some specialist areas you will find that a course from a specific old poly has higher status with employers in that field. However, for students in more traditional science and engineering fields, or those who are likely to end up at PwC, E&Y etc, we tend to encourage them towards RG because, whether you agree with it or not, a good degree from an RG is considered as a shorthand for quality by some employers, and many people recruit people like them, i.e. people from RG universities, and so the cycle continues. The students I'm mentoring aren't naturally going to have the connections and presentation skills to easily access top jobs, and they are fighting a lot of disadvantages, therefore in many cases an RG university will be a short-cut to social advancement.
However, she was very rude, and it's far more nuanced than she is presenting it. Unfortunately I do think some lower ranking universities have some not great courses, and I am not convinced that these are worth the tuition fees. I think it's unfortunate that less than academic children are pushed towards university-any university, when they might be better doing apprenticeships or technical college courses and coming out with well paid jobs and lower debt.