@davatron5000 @collinsworth This is an interesting read, though I wonder if this has less to do with compile steps and more to do with authoring format?
You talk about vendor lock-in for the compiler, but I feel the lock-in has more to do with the way you are authoring code. That anything inside a .vue or .svelte file is inherently coupled to those frameworks and is "more locked-in" than something like #Lit. That seems independent of whether or not a compiler is being run.
For example, how would you feel if #Vue or #Svelte shipped your raw templates and interpreted them at runtime? Would that be less locked-in, even though you're writing the same code? What about if Lit *required* a compiler, but otherwise was authored the same way?
I personally always disliked frameworks that fork the #JavaScript language to achieve their ends (ex. framework-specific file extensions or #JSX). I think you're describing a very similar emotional reaction I feel to those FWs, I wonder if it's the same?