@SebastianTheCrab
It's telling that you think your personal experience at Oxford in the past allows you to speak for MFL students in UK HE institutes in recent years. Were many of your Oxford peers aspiring to be MFL teachers in secondary schools?
Has it crossed your mind that it might just have been ever so slightly easier for your Oxford peers to gain access to exchange places abroad than it was for students from less prestigious universities? Which might explain why Oxford could remain outwith Erasmus.
I've observed the language skills of UK students from 15 [non-Oxbridge] universities worsen dramatically over the last 15 years, and seen them pick up slightly after Erasmus mobility here in an EU country. Almost all the incoming students from the UK and Ireland (100/year) who come to my EU university are language students, whatever your personal experience at Oxford in the past may have been.
Many of those students hope to become MFL teachers in the UK - their Erasmus mobility helps them become better linguists and provides them with cultural experience and knowledge that helps make their knowledge less abstract and allows them to enthuse pupils better.
If current MFL students don't have access to Erasmus grants and the relative ease of procedure offered by a big, structured programme, the obligatory third year abroad is likely to become unaffordable on top of fees and UK universities will be inclined to phase it out, thus making MFL less attractive and increasing dept. closures - there have already been lots of those and more are in the offing, post-Covid.
Moreover, in the past, MFL students who had an obligatory third year abroad very often worked as language assistants in other EU countries. However, those are also reciprocal: as the teaching of MFL in UK schools has decreased since becoming non-obligatory, the number of places available to EU language assistants has dwindled and therefore so have the corresponding places for UK MFL students looking to teach in EU countries.
Student mobility is not a waste of time or dimes - it allows those not fortunate enough to attend Oxford to benefit from some advantages that might otherwise be inaccessible.