They can’t do that op, they need to work to capacity. They don’t have rhe places to blanket say they will honour all offers. They need to work it in terms of capacity
Can you imagine the list of threads on MN over the next tree years, asking why their dc aren't getting enough support from their tutors / aren't getting their essays back in time / their lecturers have no time to respond to their e-mails. Do you know how much longer it is going to take a lecturer to mark 30 more essays / assignments / dissertations, or supervise projects, or pick up on pastoral issues ? Even if some universities have the capacity to physically house these extra students, and physically sit them (socially distanced ?) in tutorials etc, they don't have the capacity to magic extra lecturers / tutors up.
Someone (who lectures on a science course - thereby needing practicals) told me at their university, her course is full to capacity (which has increased over th last few years anyhow). The University management are trying to pressure them into taking additional students, as they are missing out on a lot of international student, but they are mainly students who want to study politics, economic, business studies and the like, not students who want to study her field. It really isn't anywhere near as simple as 'taking a few more students' that people are suggesting.
In addition they seriously need to delve deeper into capability. Getting a place is only the first step, being able to do the course is the next
This ^ is also crucial. You are doing the young person no good whatsoever to take them on to a course they would then struggle with.
Now, don't get me wrong, there will be deserving students who have missed out. I feel incredibly sorry for them. I also speak as a parent who has spent the last two days supporting my dc to grapple with clearing. But you are over simplifying this. There are always students who don't get the grades they were aiming for (I understand about 25% of applicants don't get taken in to their first place University each year). It is just this year people have a single excuse to blame, rather than having to understand that it is a competition and that means there will always be some who lose, usually for a lot of different reasons.