Though JavaScript is of course not mandatory, the mind set and incentives in which web specs have been created by browser vendors is bound to pile up complexity

Though JavaScript is of course not mandatory, the mind set and incentives in which web specs have been created by browser vendors is bound to pile up complexity, in that developing a browser from scratch is considered infeasible (last one to try was Opera), and browser vendors are rather trying to turn existing browser code bases into universal runtimes for apps. Point in case: WASM, which I consider bloated and out of place in a web browser.