Is it really that much for the browser vendors to support TypeScript? Then, the only reason to compile would be to optimize for production by removing the excess code of the data-typing.
Browser support for TypeScript would invite developers to use those browsers, which aligns with browser-vendor interests.
My two cents: Formal Methods (e.g., "Z" and Promela) and also, teamwork stuff (from old days, Team Software Process, and any more modern material like that).
It would be really nice to not always have to do a worker thread or iframe to get multi-threading. Web apps with more involved and/or extensive ui's would benefit a lot from this in terms of the ui responsiveness.
Kind of surprising that the article doesn't mention the profits and sway that Big Tech has to afford the approaches he describes. Borrow money very cheaply, buy back stock, profit from higher stock price. As well, Big Tech has market power (not necessarily monopoly) to allow for a lot of flexibility in deadlines.