1. They coordinate the submission of papers, and their dispatch for peer review.
2. They handle layout, typesetting, copyediting, etc.
3. For journals with print editions (of which there are many), they handle distribution.
All of those things could be replaced by the internet, but they take time, and they cost either time or money. And I much prefer reading journals with professional typesetting over those that rely on LaTeX.
There's also just the weight of history - many "good" journals aren't open access, and an academic's career trajectory is largely determined by publishing in those good journals. Going exclusively open access (in many fields) is either:
1. Expensive (paying for open access publication in a commercial journal)
2. An affectation by senior people who already have established careers
3. A huge risk by junior researchers making a principled stand at the cost of potential damage to themselves.
If anyone is wondering "how much do points 1 and 2 cost?!" the financial overview of notorious not-for-profit publisher PLOS is a good starting point: https://www.plos.org/financial-overview
If you create an electronic document of a few MByte size, 1500$ should cover hosting it for the next 1000 years!
The largest cost (besides writing the paper) is reviewing it and that cost is already externalized by publishers.
1. They coordinate the submission of papers, and their dispatch for peer review.
2. They handle layout, typesetting, copyediting, etc.
3. For journals with print editions (of which there are many), they handle distribution.
All of those things could be replaced by the internet, but they take time, and they cost either time or money. And I much prefer reading journals with professional typesetting over those that rely on LaTeX.
There's also just the weight of history - many "good" journals aren't open access, and an academic's career trajectory is largely determined by publishing in those good journals. Going exclusively open access (in many fields) is either:
1. Expensive (paying for open access publication in a commercial journal)
2. An affectation by senior people who already have established careers
3. A huge risk by junior researchers making a principled stand at the cost of potential damage to themselves.