> why don't you just host your papers on your website then - or, if you do, why don't you think it's enough?
Most publishers prevented you from doing this as of a few years ago (I left academic research around that time). You were not allowed to post any content that contains any work by the publisher (even formatting/editing changes after first round of reviews). Thus you could only publish a "preprint" which no-one can rely on to cite because they don't know what's in the final peer-reviewed version. Some publishers are more lenient than others but there's definitely friction induced.