I mostly agree, but would add two caveats.
Relying too much on getting one very specific advisor is risky. Most advisors are middle-aged (or outright old), especially those with Nobel Prizes, and they do sometimes die or move away with little notice. If that happens, universities can be very bad about finding replacements (let alone comparably brilliant replacements) for any students cast adrift.
Also, an adviser's personality & schedule are as important as their research skills: a Nobel Prize winner who's usually away giving speeches, and is a raging, neglectful arsehole when they are around, is likely to be more of a hindrance than a help in getting a PhD. Put like that, what I just wrote is obvious, but I can imagine it being the kind of thing potential applicants would overlook.
Among my friends interested in rationality, effective altruism, and existential risk reduction, I often hear: "If you want to have a real positive impact on the world, grad school is a waste of time. It's better to use deliberate practice to learn whatever you need instead of working within the confines of an institution."
While I'd agree that grad school will not make you do good for the world, if you're a self-driven person who can spend time in a PhD program deliberately acquiring skills and connections for making a positive difference, I think you can make grad school a highly productive path, perhaps more so than many alternatives. In this post, I want to share some advice that I've been repeating a lot lately for how to do this:
That's all I have for now. The main sentiment behind most of this, I think, is that you have to be deliberate to get the most out of a PhD program, rather than passively expecting it to make you into anything in particular. Grad school still isn't for everyone, and far from it. But if you were seriously considering it at some point, and "do something more useful" felt like a compelling reason not to go, be sure to first consider the most useful version of grad that you could reliably make for yourself... and then decide whether or not to do it.
Please email me (lastname@thisdomain.com) if you have more ideas for getting the most out of grad school!