The website linked above is just a way to read journals online, hosted by Johns Hopkins. As it states, "Most of our users get access to content on Project MUSE through their library or institution. For individuals who are not affiliated with a library or institution, we provide options for you to purchase Project MUSE content and subscriptions for a selection of Project MUSE journals."
Someone has to foot that bill. Open-access publishing implies the authors are paying the cost of publication and its popularity in STEM reflects an availability of money (especially grant funds) to cover those author page charges that is not mirrored in the social sciences and humanities.
Unrelatedly given recent changes in federal funding Johns Hopkins is probably feeling like it could use a little extra cash (losing $800 million in USAID funding, overhead rates potential dropping to existential crisis levels, etc...)
No it implied the journal not double-dipping by extorting both the author and the reader, while not actually performing any valuable task whatsoever for that money.
Like with complaints about landlords not producing any value, I think this is an overstatement? Rather, in both cases, the income they bring in is typically substantially larger than what they contribute, due to economic rent, but they do both typically produce some non-zero value.
This particular journal is published by Kent State University, which has an endowment of less than $200 million.
But science? That's something that IMHO should be paid for with tax money, so that it is accessible for everyone without consideration of one's ability to have money that can be bled.
Sure for me, $20/mo is fine, in fact, I work on AI systems, so I can mostly just use my employer's keys for stuff. But what about the rest of the world where $20/mo is a huge amount of money? We are going to burn through the environment and the most disenfranchised amongst us will suffer the most for it.
Aka not happening.