The value of a Ph.D isn't in the knowledge you learn or papers you read, it's in demonstrating the ability to take on a vaguely-specified original research task where you can't see the eventual outcome at the beginning, and drive it forward until you come up with something useful. All without having the support of other people who actually know what they're doing to guide you. If you're measuring knowledge by what you've learned from papers, you're missing the point.

There are other ways to develop this skill. I've never once felt hampered by the lack of a Ph.D, but that's because fairly early on in my career, I took on tasks that were scary, that nobody knew how to do, and drove them forwards until they were useful to other people. But it does require following through on original work, and pushing your projects forwards even when other people think they're a bad idea, and accepting responsibility for results rather than effort or ability.