Seems like this is more for the hobbyists - building webpages for the love of the act. Frameworks are built to be standardized, enforce best practices via their design, and allow developers to 'hit the ground running', so to speak.
No web site is intrinsically valuable - the information and functionality it wraps is what holds its value. Developing the access to that information and function, enforcing correctness, and the timeliness of that development is what frameworks empower orgs to deliver at much lower cost in the present and future, vs. vanilla web dev.
You can't overstate how often decisions are large orgs are driven by hype, follow-the-herd, or "use popular framework X because I won't get in trouble if I do" mentalities. The added complexity of tools can easily swamp productivity gains, especially with no one tracking these effects. And despite being terrible decisions for the business, they can align with the incentives of individual decision makers and teams. So "people wouldn't do it if it wasn't a net positive" is not an argument that always holds.
I see absolute messes created out of React and associated frameworks. Quite possibly because, “you’re holing it wrong”. Just using a framework is not going to force best practices and it’s very easy to create terribly bloated and slow systems with these tools if you’re not thoughtful.
No web site is intrinsically valuable - the information and functionality it wraps is what holds its value. Developing the access to that information and function, enforcing correctness, and the timeliness of that development is what frameworks empower orgs to deliver at much lower cost in the present and future, vs. vanilla web dev.