Everyone in JS-land seems to have an opinion about how tooling should work, and because the platform (well, Node at least) provides no opinions of its own, everyone goes ahead and implements it. So you end up with a thousand-and-one competing bundlers, linters, formatters, test runners, etc, with all the associated churn and cost in learning it all and getting a new project up and running.
Compare that to something like Go which includes all of that stuff out of the box—by and large everyone has just said "yep that seems to work" and stuck with the defaults.
I think the second problem is the browser still fundamentally wants to be a displayer of documents. Yes there has been continued additions of new APIs over the years that have made the SPA pattern much easier to work with, the fact of the matter is you can still save yourself about an order of magnitude of complexity if you can get away with your app being an "old school" multi-page affair.
Compare that to something like Go which includes all of that stuff out of the box—by and large everyone has just said "yep that seems to work" and stuck with the defaults.
I think the second problem is the browser still fundamentally wants to be a displayer of documents. Yes there has been continued additions of new APIs over the years that have made the SPA pattern much easier to work with, the fact of the matter is you can still save yourself about an order of magnitude of complexity if you can get away with your app being an "old school" multi-page affair.