> Asynchronous communication across timezones has not been solved, and I struggle to see how it would be.

I disagree, at least if we are talking about what tools to use. But many people who are used to being face-to-face aren't used to async. Async communications require patience, foresight, and good writing skills. You need to envision the end result of the collaboration, provide as much of your perspective as possible without writing a wall of text, and ask good questions. Then, in 8 hours, your coworkers do the same. And over a few days, consensus arrives.

Easier said than done, I admit. It takes time and deliberate practice to do this well. It is not how people are used to collaborating. But that does not mean it doesn't work - it means people only succeed when they put in the effort learn new communication skills.