This MDN page is where I first discovered the <template> element, and I wasn't very impressed: verbosely operating on one textContent at a time, using ordinal indices into very untyped querySelectorAll results, apparently gratuitous complications with document fragments and shadow DOM.

Verbosity never concerned me. Readability, maintenance, page weight and separation of concerns does.

Typically I do not find myself using querySelectorAll within the context of a template element. When I do I am usually applying changes universally to all of the matched children within the element. The CSS class of the element reflects these things semantically. I find this highly readable. It also resolves most concerns around the type of the element.

Of course in Vanilla JS, types are a mess. Even Microsoft's finest duct tape script doesn't fully resolve these issues. Overall I find Vanilla JS and browser APIs to be a lesser evil than the build systems, package managers and indirection of the React/Next.js approaches. After all, these compiled environments and their libraries will boil down to Vanilla JS when deployed in the browser.