Most people struggle to be efficient and effective at written communication. There are a huge number of people with good technical skills whose writing skills don't go much beyond writing a string of one-liners on Slack. And particularly in the younger generations, there is an enormous amount of resistance to anything that looks like detail-oriented long-form writing. In-person interactive discussion is much easier for people without these skills.

It takes years of practice to become proficient at this, even if English is your native language. Everyone wants full-time remote but few people possess the communication skills to effectively work asynchronously and I see very few people intentionally trying to develop these skills or being willing to put in the many hours of work required.

This may be the primary essential gap for remote: people need to dramatically improve their written communication skills. Until they do, they lack the skills to work remotely effectively.

Ironically, we used to do asynchronous highly technical long-form discussions over email and on mailing lists. It is where I developed a lot of my writing skills, and this used to be the norm. It worked pretty well and some older open source projects still work this way. Now everyone hates email because it forces them to write.