Complete aside here but... Casting Agents don't exist. There are Casting Directors who shrivel up howling when someone calls them a 'casting agent' and there are Agents.
I have been in casting. For the last 30+ years I have been an agent. There is no such thing as a Casting Agent.
Setting that aside - it is worth thinking very hard about the fact that a drama school will have a large body of work across the 3rd year along with a London showcase which is how agents tend to pick people up, with a lot of actor/agent meetings happening after Christmas in the third year Spring term. Many of the top drama schools will have 50% or more of their students signed to agents before showcase. University drama courses mostly don't have this so you come into the world unseen. It is currently showcase season and I will have seen many young graduates in shows or at showcases for the drama schools by the end of this month, but I haven't seen anyone from a uni course because they just don't run in the same way.
Someone upthread mentioned ALRA - as an industry we are all currently trying to help the ALRA students and Rose Bruford has stepped in and is taking all ALRA South's students on. Casting directors are arranging sessions with both ALRA S and N as they haven't had a showcase and agents are meeting people to help either offer them representation or to steer them.
There are always people who are so talented or so in the right place at the right time that they move forward without being drama school graduates, but in the current business as we all stagger back post covid, that drama school grounding helps. Equally, there are always people who have given up the business within two or three years because they just aren't the current favourite thing in looks or because they discover they just can't cope with the rejection and the way the world is or they jsut want to do something else. I have had people go off to be yoga teachers, psychologists, lawyers, experts in company takeovers - you name it. Over the years I've seen so many incredibly gifted kids stop while others less gifted have risen to the top but that's the way of many professions and doubly so in this industry. When I first came into the business many years ago the Equity statistic was that over 95% of actors were out of work at any given time. That has, I think, risen to something like 98%.
The long and the short of that is that if someone can get in to a good drama school they should and if they get in to a not so well known uni that may not be the stepping stone they want but there's not much certainty on career progression either way to be honest.