I think that it depends on the size and number of your projects. The fact that Go has the equivalent of Sinatra/Flask/Express in the standard library is really cool, but that isn't always what you need.
At work we have several dozen applications in service for multiple customers, and almost every single one needs more than that: authn, authz, I8n, DB schema management, a REPL for support work (debugging and data amends), standardized layouts and components from easy switching between projects etc. etc. If we were a larger org with even more applications we would probably benefit from microservices, but actually, Rails-style monoliths are exactly the right fit for us. If we didn't have a framework we'd have to pick a set of components and maintain the glue code to stitch them together, then re-use across products: IOW, we'd end up making a framework if there wasn't one already. At my last job, that actually happened.
At work we have several dozen applications in service for multiple customers, and almost every single one needs more than that: authn, authz, I8n, DB schema management, a REPL for support work (debugging and data amends), standardized layouts and components from easy switching between projects etc. etc. If we were a larger org with even more applications we would probably benefit from microservices, but actually, Rails-style monoliths are exactly the right fit for us. If we didn't have a framework we'd have to pick a set of components and maintain the glue code to stitch them together, then re-use across products: IOW, we'd end up making a framework if there wasn't one already. At my last job, that actually happened.