This is something I hear all the time about publishers, and it used to resonate with me, too, until I started to work for a publisher and realized how much goes into the system we have beyond just putting manuscripts online. The real eye-opening thing for me was talking to editors and seeing all the behind-the-scenes stuff that they do. They have to know enough about their field to know what's worth sending out for review in the first place, manage the review process so that you don't have nasty, unhelpful reviews or personal vendettas getting exercised, manage ethical concerns, deal with authorship disputes, etc, and that's just the review piece of things. There's a whole information infrastructure behind the scenes making sure that once something is published that it can be found, indexed, searched for, aggregated by author, connected to the data and code and protocols and other entities that it mentions... I mean, I've been at this for 8 years and there's still so much I don't know.
All that just to make the point that the value proposition is still very much there, though I'll agree publishers could do more to make this apparent.