1. Proxies are painful to say the least on TS.

2. Code completion can be done also without static typing. Also relying on code completion is a strong smell of a bad codebase. The "very strong arguments" rarely have any empirical basis.

3. Transpilers/compilers are bad and more transpilers are worse. I would prefer a pure browser framework though. A lot of projects would be and are fine without treeshaking, minification etc. And those are practically never needed for development where the compilation step causes most harm.