> optimization opportunities that cannot be reasonably implemented on top of a JS-based templating engine You very much can do those optimizations in pure JS.

> optimization opportunities that cannot be reasonably implemented on top of a JS-based templating engine You very much can do those optimizations in pure JS. lit-html's repeat() directive implements the list diffing approach used in ivi, Vue. It's invoked just like a higher-order function over an array and a mapper function: https://lit-html.polymer-project.org/guide/writing-templates#repeating-templates-with-the-repeat-directive https://lit-html.polymer-project.org/guide/writing-templates... I also don't think custom syntax is necessary or that useful. JavaScript has enough abstraction power in functions and objects that you can build very nice embedded DSLs without a compiler or custom template syntax. but my main point is that both approaches are still valid, and rather than choose a framework based on its particular DX, we should move away from frameworks and be able to write individual components with whatever DX the developer wants, and have them all work together.