> journals should not be the arbiters of quality

It is the editorial board, i.e. academic peers, not the publisher, that are (?were) the arbiters. As far as I can see, the primary non-degenerate function of journals is to provide a quality control mechanism that is not provided by "publishing" on your own webpage or arxiv.org. If journals really are going to abandon this quality control role (personally I doubt it) then I fail to see their relevance to science and academic discourse at large.

Indeed, they are irrelevant. Right now they maintain an administrative monopoly over the peer review process, that makes them de-facto arbiters even if it's peers doing the work.

Journals should either become tech companies offering (and charging for) new and exciting ways to present scientific research, or simply stop existing.

I agree, and...

Completely off topic, but thanks for creating AudioMulch, I don't use it actively anymore but it totally revolutionized how I approach working with sound!

At the end of the day, I expect a journal that I pay for to be better than arXiv and that means quality control. Few people have the time to self-vet everything they read to the extent that it should be in absence of other eyes