I don't think there's much to gain from playing the blame game. Everyone is different and none of us can know what was going on with these poor Bristol students. Also, sometimes one suicide inspires another, so there could have been an element of that.
But the suggestion that students with MH issues avoid going to university is a little extreme, Often academically gifted students also have MH issues. It would be a shame, and a potential loss to academia and society, if they were discouraged from post-secondary education! Other times, MH problems don't manifest themselves until university.
Also, you can't assume they weren't getting help or taking antidepressants -- in fact, the British Medical Journal and Lancet have both published research indicating that for teens, ADs frequently don't work or can have a higher risk of suicide. If the students were 18 or 19, they were still biologically teens even if they were officially "young adults".
But whether it's helicopter parenting, financial pressure, the result of a public school education (or lack thereof), or something in the water, I think universities need to respond to the reality that a significant number of students run into MH problems, and consider what constitutes a reasonable amount of pastoral care.
People with MH issues are often incapable of asking for help -- it's not like having a broken leg - so a system that requires troubled students to seek help doesn't work well for MH.
DD's uni has an excellent tutorial system (no, it's not Oxbridge!). Students have regular small group meetings with their tutors. This, in itself, is valuable on the academic side, but tutors also know if a student starts falling behind with coursework (often a sign of MH trouble) and can reach out to the student instead of the student having to ask for help. I don't know what it costs the uni, but would be great if it were more common for undergrads.